> The optional marking is with the dative case ending. I do not seeOf course not. That would be accomplished by *-yo.
> the relevance. Surely there were no possessive endings sitting on
> the possessum in PIE helping to show the construction.
> Certainly not because of a rule pertaining to word-final position.So tell us where **ye-syo is to be found then.
> Inside the word the thematic vowel should alternate and does so in
> verbs and pronouns,