@porsche - "the standard rule, whatever that may mean" - I simply said this because I had found it on many websites, for example:

grammar websites, such as: grammar.about.com and the Grammar Book, which I've already mentioned, and Grammar Monster, which says

"Finally, joint ownership is shown by making the last word in the series possessive; whereas, individual ownership is shown by making both (or all) parts possessive. - Andrew and Jacob's factory (joint ownership), Andrew's and Jacob's factories (individual ownership)"

academic writing sites, such as the Owl at Purdue and this from Kent Law at the Illinois Institute of technology -

"A less-often faced decision involves the use of apostrophes where multiple owners are named. Where two or more people own one item jointly, place an apostrophe before an "s" only after the second-named person.... However, when two or more people own two or more items separately, each individual's name should take the possessive form"

But I'm quite happy to change "standard rule" to "widely accepted principle" or "standard pattern" (as below) or something of that ilk. As far as I can see, none of these sites address the question of pronouns. I think, however, that what I said to Erin is more or less line with the answer they give at the Chicago Style forum you linked to. I've also found an excellent answer at one of my favourite sites, Professor Bryan's Common Errors (at Washington State University) -

"The standard pattern is to treat the two partners as a single unit—a couple—and put an apostrophe only after the last name: “John and Jane’s villa,” “Ben & Jerry’s ice cream.” Add more owners and you still use only one apostrophe: “Bob and Carol and Ted and Alice’s party.” ... But when you begin to introduce pronouns the situation becomes much murkier. “Jane and his villa” doesn’t sound right because it sounds like Jane and the villa make a pair. The most common solution—“Jane’s and his villa”—violates the rule about using the possessive form only on the last partner in the ownership. However, most people don’t care and using this form won’t raise too many eyebrows."

http://public.wsu.edu/~brians/errors/jointposs.html (not the same as the previous link)

But apart from the Wikipedia article I've still seen nothing to say what happens when a person is what is being "jointly possessed". Perhaps you have some ideas. I can only assume that as the principle/pattern I've been talking about seems only to apply to non-human elements, normal apostrophe "rules" apply.

There used to be quite a good site for AP style called Newsroom 101, which also dealt with this sort of thing, but it seems to have been hijacked.

@colin shaw - from Fowler's (Third edition) - "In BrE it is in order to use either a plural
verb or a singular verb after most collective nouns, so long as attendant pronouns are made to follow suit: 'when the jury retires to consider its verdict 'or 'when the jury retire to consider their verdict'. The same principle applies to all the main collectives like army, audience, clan, company, court, crew, folk, government, group, herd."

According to you, "people like yourself have forgotten what is actually correct". No, I'm afraid it's "people like you" who jump to conclusions without bothering to check with Wikipedia or any of the other sources I mentioned. This principle is very well known on grammar sites. And what the German grammar lesson had to do with anything beats me.

http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv358.shtml

http://blog.oxforddictionaries.com/2011/09/agreement-over-collective-nouns/

http://www.onestopenglish.com/grammar/grammar-reference/american-english-vs-british-english/differences-in-american-and-british-english-grammar-article/152820.article

http://separatedbyacommonlanguage.blogspot.com/2007/07/collective-noun-agreement.html

As a Scot myself, I would probably refer to Scottish fans, but I think this is just a usage difference. The figures for the Scotsman and the Herald are about equal for Scotland and Scottish, for both supporters and fans. And both papers refer to both the Scottish team and the Scotland team. Personally I wouldn't say anything team, simply the name of the country. "Holland are playing Denmark" "Scotland are playing really well at the moment", but that doesn't make other people wrong.

Where I might agree with you is that when Scottish fans go on the rampage they are always Scottish, but on one famous occasion when the English did the same, Margaret Thatcher, the then Prime Minister, announced that it was a sad day for Britain. Wait a minute, was our reply.

@Skeeter Lewis - "If there is an example of a reputable British author using this form more than say thirty years ago ...". That's a bit of a tall order! It would be like looking for a needle in a haystack. The third edition of Fowler's (1996) might be of some help, however. In it, Burchfield says that group possessives "normally only require an apostrophe after the last element" and gives the example (amongst others) of "my uncle and aunt's place".

OK, here we go (all from Google Books searches):

J.B.Priestley, Bright Day 1946 - "These were chiefly members of my aunt and uncle's whist-drive circle"

Richard Bentley (publisher of "The Classic Novels", London) 1810 - "Mr. Grey paid her the day he had obtained (for it was not easily obtained) my father and mother's consent to fix that of his happiness"

Sir Walter Scott 1833 - " lawful inheritor of my father and mother's joint estates"

Punch magazine 1842 - "My name is DIDDLETON D00; I am a descendant, both by my father and mother's side, from the great Doos of Osnaburgh-street"

Shakespeare, Macbeth - "My wife and children's ghosts will haunt me still"

William Pinnock, A Comprehensive Grammar of the English Language, London 1830 - 'When two or more genitive or possessive cases are united by the conjunction and, the last only receives the apostrophe; as, "It was my brother and sister's wish;" but if a disjunction, or other kind of words intervene, all the genitive cases retain it'

But I grant you that Samuel Richardson uses the double apostrophe a couple of times.

@Erin - Both "Jane and John" and "Jane and John's house" are most certainly noun phrases, at least in the way the term is used in linguistics. And they can also be subjects, but in your example "Jane and John's house" there is no verb and therefore no subject. But if we took a sentence - "Jane and John's house isn't far from here" - In form "Jane and John's house" is a noun phrase, whereas in function it's the subject (whether it's compound or not is less important). Noun phrases can also function as direct and indirect objects and a few other things.

@porsche - I hadn't realised I was confused, but I'll dig around a bit (and look at your Chicago Style link) when I've got a bit more time.

@colin shaw - in terms of "good grammatical rules" when using group nouns, sports commentators are only following standard practice in British English; just look at any British newspaper, British grammar book or British usage guide, or the Wikipedia article linked to above. This is sometimes called "notional agreement" and is the way most of us Brits naturally think about these things.

And what on earth is wrong with England supporter, after all we have Arsenal supporters, Liverpool fans etc?. You wouldn't normally talk about a Liverpudlian supporter (they might support Everton!). I see plenty of people in Poland wearing England T-shirts, but they're certainly not English. What is important is who they support, not their nationality. And a supporter of England sounds a bit long-winded to me.

A site search of the Guardian brings up these figures (and remember "supporter of / fan of" won't necessarily be about sport):

England supporter - 271
English supporter - 58
supporter of England - 4
England fan - 746
English fan - 220
fan of England - 26

and for comparison

Scotland supporter - 18
Scottish supporter - 7
supporter of Scotland - 1 (but possibly about the country, not the team)
Scotland fan - 63
Scottish fan - 16
fan of Scotland - 0 (1 about the country)

The ratios seem pretty consistent and conclusive to me. Again you may not like it, but it's certainly common usage.

Hi Erin - in your original comment you wrote "If referring to their separate homes, however, it would be phrased as "Jack's and Jill's house." I assumed you were talking about two separate houses, but perhaps you meant two homes in one house. But I think the important thing is their possession of the noun in question.

As regards ambiguity, with "Jack and Jill's house, we know there are two people and one house, buy in Skeeter's example sentence - "I met Anne and Joe's aunt at the airport." - who did I meet? Anne, who was accompanied by Joe's aunt (so two people) or the woman who happens to be the aunt of both Anne and Joe (so only one person).
There is another (unintentional) example at Wikipedia that shows this ambiguity - "Jason and Sue's dog died after being hit by a bus". The writer of the article seems to think that it is clear that only the dog died, from context, but another contributor is not convinced, and I'm not sure I am either.

http://en.wikipedia.org/wiki/Apostrophe#General_principles_for_the_possessive_apostrophe

The problem with Mignon Fogarty's piece is that she only talks about things; in fact I've yet to see any guidelines about the "possession" of a person, but I haven't looked that hard yet.

OK, sorry, I misread your sisters example, but I don't think it makes any difference - either "my sister's and my childhood" or "my sisters' and my childhood" seems fine to me. But don't think your other example, without the possessive s, works. I think you have extrapolated a rule for two proper nouns (ie; Jack and Jill) to a common plural noun and pronoun, and I find the result ambiguous.

You may well have hit an area where there simply isn't an accepted rule and you just have to play it by ear. Remember the apostrophe is the most recent punctuation mark to enter English. I'll finish with a comment from Professor Brians at the excellent Common Errors - "First let’s all join in a hearty curse of the grammarians who inserted the wretched apostrophe into possessives in the first place. It may well have been a mistake."

http://public.wsu.edu/~brians/errors/apostrophes1.html

@Skeeter - as I understand it, the standard rule for when two people own an OBJECT is one apostrophe - Jack and Jill's house (sorry about the caps, but I can't see any other way to add emphasis) . When two people own two separate objects - two apostrophes, plural houses - Jack's and Jill's houses (I think Erin accidentally missed out the plural s in his example)

I agree, however, that "I met Anne and Joe's aunt at the airport." is ambiguous, and when we are talking about a relationship with a person then it's a good idea to add an apostrophe to the first name. But when we are talking about the possession of a thing, there is no such ambiguity, and the widely-accepted rule that Erin is quoting refers specifically to things.

http://owl.english.purdue.edu/owl/resource/621/01/
http://www.grammarbook.com/punctuation/apostro.asp - (rule 8)
http://grammar.about.com/od/punctuationandmechanics/tp/GuideApostrophe.htm

@Erin - the standard rules don't seem to mention anything about pronouns, only proper nouns. From all the double possessive possibilities, I'd go for "Mike's and my house" or "My sister's and my childhood" at a pinch, but Ï find them a bit awkward, so I'd probably try and rephrase it: "The house belongs to Mike and me", "This is the house Mike and I own" or "This was when my sister and I were children".

However, there are quite a few instances of "my sister's and my childhood" in published books:

https://www.google.com/search?q=%22my+sister%27s+and+my+childhood%22&btnG=Search+Books&tbm=bks&tbo=1

Hi HS
I've left a contact address by your comment. (What are PMs? :) )

Sorry jayles, I'm not playing any more. I'm not a Saxon nationalist, so the whole premise of your argument completely passes me by. It seems that the Anglish supporters will brook no discussion except on their terms, and brand anyone who disagrees with them a Latin-lover or arse-licker, and think that telling people not to get their knickers in a twist somehow constitutes an argument. I've had enough.

@AnWulf - "It's hard for folks who hav spent years learning the latinates (as well as stupid spellings) to let them go." - Not only pretentious but condescending and insulting to British spelling.

@Galitrot - time will indeed tell

Meanwhile I'm going back to real English, as it seems a rational conversation is impossible here - I tried but all I get is preached at by the faithful. I respect your knowledge in Old English, but not your disdain for the natural language and vocabulary spoken by the vast majority of English speakers.

@Ængelfolc - why is it that when people want to prove something is bad in English they always choose the most preposterous example they can think of? And I'm sure you realise that "school" came into Old English via Latin from the original Greek skhole, and that "proper" came from the Latin proprius via the Old French propre. So what exactly are you trying to prove? Not to use long words? To cut down on nominalisation? No argument. But that doesn't mean you have to judge every word by how came into the language centuries ago.

And as far as I'm concerned, using words like "fremd", listed by the Free Dictionary as "Archaic - alien or strange" instead of foreign, or "othersome" instead of different (jayles) is indeed just as pretentious as using words like "enhancement", if nor more so. At least most of us know what enhancement means. Distinction can mean difference, and by using such words you are indeed differentiating yourself from the bulk of English speakers; your little band apparently know better than your fellow speakers.

And what the hell is "true English" when it's at home? Sounds too much like the "true religion" to me.