@porsche ... OE did hav duals. We still kind of see it with the word two added ... "What are you two doing?" After two, it becomes plural (OK, I hav heard three but after that!) ... "What are y'all doing?"

@sigurd ... It's not that English lacks a sunder 2nd person plural form, it's that grammarians and pedants spurn the informal ones like y'all. Thus, none of them are taught worldwide. As a Southerner, y'all (maybe it is time to drop the ' ... yall) rolls off my tung eathly and often.

If one were only looking for a plural form for the subj. and obj. cases, then ye could slide into that but then there are still the poss. forms to deal with. But ye has baggage. Thanks to the effort of many to copy the French/Latin way of using the plural for a polite singular, Ye became associated with a kind of snobbery. That was part of the grounds for it falling out. Thou got caught up in this by association. So you took over for both the subj and obj. as well as sing. and pl. If there were an attempt to bring back ye, then there would likely also be an attempt by some to use it as a polite singular ... which would lead to dying again eftsoons.

Bring back thou has its own problems. Mainly that it has a separate verb form. Folks aren't going to bother when it isn't needed.

The plural problem is solved in different ways. In the South there is y'all (you all) as both the subj and object, yalls for the poss. In the northeast, there is youse (you+s), in the mountains, I'v heard youins ... up north, they say yu guys. So there are several forms for the pl you and they can't be turned into a polite sing. form to befuddle everything again ... It's only that none of them are are in the grammar books and formally taught. English may be lacking a formal plural form, but there is no dearth of plural forms to be found!

Again, I refer you to the Bible passage above which shows the right usage. It was written in the 17th Century. Saying "established since the 15th century" is nonsense. It was this type of misuse that was among the reasons that it died out. Repeating an error will not bring it back into usage.

There's nothing "to be practical" about. It simply isn't used in modern English. If you use it wrongly, then it will clash with what folks do know about from the Bible. Again, it is recognizable but rarely used outside of religious contexts. If you use it only as the objective plural, then what about the subjective plural? You can't have one without the other.

How are you going to use it? I see ye ... you can't hide from me! ... Sounds like you're talking to one person. ... I see ye ... y'all can't hide from me! ... Sounds ... well, silly and confusing. Better to say, I see y'all ... y'all can't hide from me. Then everyone knows you're using a plural.

Good luck!

Actually, to my surprise, in OE there was mēdgilda

mēd = meed - deserved share, reward
gild = compensation (guild or yield)
a = er

some who gets his deserved share of compensation ... a pensioner ... could also be a mercenary! lol

So I guess today it would be something like meedgilder, meedguilder, or meedgetter? (I don't think meedyielder works since that looks like you're yielding the meed rather than getting it.) Or if you like gelt ... geltgetter? I like either meedgilder or meedguilder.

Well I do hav two unopened bottles of wine ...

To be a little more right ... silly comes from sælig. But we could keep the old greetings using the old forms ... just as folks often say wassail at Christmas and hav no idea of what it means! lol ... It's a smashing together of "wes hal" ... or the longer form that I brook: wes thu hal (wes þu hal).

So we could say, "Glad Yule(tide) and Gesaelig New Year!" as idiomatic.

Which is all better than wansaelig ... unhappy.

Yes, ye ... in the late phases ... can be found being used as the objective ... but again, it was not correct to do so ... and would not be correct to do so now. It was part of the whole confusion that led to thou and ye being dropped altogether. You'll also find thee being used as the subject as well ... again, that's wrong. "You" is the right objective form for ye.

Genesis 19:8 KJV
Behold now, I have two daughters which have not known man; let me, I pray you (obj pl), bring them out unto you (obj pl), and do ye (subj pl) to them as is good in your (poss pl) eyes: only unto these men do nothing; for therefore came they under the shadow of my roof.

Most of the time the KJV gets it right (but sometimes, even it mixes them up).

You would be understood. Just as folks are understood when they say, "John and me went to the store." ... It should be John and I. So if you mix 'em up, you'll be understood. It just won't be "right".

And since thou, thee, and ye are no longer taught, most folks don't know the proper forms. Only a few folks like me will notice. I see folks writing fantasy stories trying to use them and messing them up. They also use the old 3rd person sing. ending -eth with other pronouns ... which is also wrong ... or, just as wrong, they use the old -en verbal plural ending in the singular. They're simply not taught, the forms are rarely used, and most folks don't know.

Your and yours ARE the plural forms (see Bible passage above). Thy and thine were the singular forms.

(one) Thou must not forget thy book. ... It's not mine, it's thine.
(many) Ye must not not forget your books. ... They're not ours. They're yours.

Nowadays, Thou, thee, thy, and thine are not used ... thus you, your, yours are now both sing. and plural. This leads to informal plural forms like y'all.

Where are y'all going?
Are these y'all's books? (Again ... these are "informal".)

If you're writing a fantasy story and want to use them, then the correct way is the way I have outlined. Thou, thee, thy, and thine in the singular and ye, you, your, yours in the plural.

Thou and ye ... and you.

Let me see if I can help straighten this out.

thou - 2nd person nom. sing.; thee - 2nd per. obj., thy, thine - possessives (like my, mine)
ye - 2nd person nom. pl.; you - 2nd per. obj. pl.; your, yours -possessives pl.

So:
thou (subject) - thee (object)
ye (subject) - you (object)

Later, copying the French use of tu - vous, ye became a "polite" sing. This caused a lot of confusion and angst ... owing to this, and other things, gradually both thou and ye dropped out as "you" took over both the sing and pl nom. forms and remained the obj. form as well. This is not surprising since "you" is a near homophone with "vous" ... and in the French centric times, it would have eathly slipped in. Since your, yours go with you then they also picked up the sing. use.

You might see "ye" being used as the objective form, but this is an error (albeit a somewhat common one).

Ye have was contracted to yave or y'ave:

To the Kyng ... of your grace especiall Y'ave graunted ..."Rotuli Parliamentorum", c1472

These are considered archaic/dialectal. While most modern speakers don't use them, they would know them ... However, they likely wouldn't know the contractions as they are rarely seen. So I'd stay away from them.

If for some reason, thou art going to benote these words, knowest thou that thou has its own verb form:

Now are we sure that thou knowest all things, and needest not that any man should ask thee: by this we believe that thou camest forth from God.
- John 16:30 KJV

glæd means glad ... gesælig means happy (as does sælig)

Glæd Geol and Gesælig Niw Gear. ... Glad Yule and Gesilly(?)/(ME sely) New Year

@Talvieno ... It wasn't from a few folks learning Choctow. Back in the early 1800s, Choctaw was the lingua franca among the Indians that region ... Remember, much of Southeast beyond the mountains was sparsely settled ... I think Memphis was founded in 1815. So the settlers would have had extensive dealings with the Choctaws themselves as well as the language ... It is such a useful word that it passed into English.

@Cdw ... the ola kala theory falls short in many respects. First, as I noted above, it doesn't fit the timeline.

Second, OK began in the US. If it were from Greek shipping documents, it would have been in widespread use umbe the world before being spread by Americans.

Third ... J.F.W. Dorman is said to have been the first to actually commercialize the making of rubber stamps in 1865 ... Some 50 years after the first recorded use of OK so the Greeks couldn't hav been stamping "OK" before that ... so again, it fails the timeline.

It is also often claimed that a ‘word’ is not a ‘word’ (or is not ‘English’) unless it is in ‘the dictionary’. This may be acceptable logic for the purposes of word games, but not outside those limits. … OED preface, 2000 http://www.oed.com/public/oed3preface

As it so happens, the word is in the wordbook:

dictionary.com:
con·ver·sate  [kon-ver-seyt] Show IPA
verb (used without object), con·ver·sat·ed, con·ver·sat·ing. Nonstandard except in some dialects .
to have a conversation; converse.

M-W:
Definition of CONVERSATE
intransitive verb
nonstandard
: converse 2a
Origin of CONVERSATE
back-formation from conversation
First Known Use: 1973

Wiktionary:
Etymology
Back-formation from conversation.
conversate (third-person singular simple present conversates, present participle conversating, simple past and past participle conversated)
(African American Vernacular) To converse, to have conversation.

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It is a word ... not one that I would use, but it does exist (as does ain't). But, for that matter, I don't use the word converse either ... I use the word TALK!