Plural possessive

When the bambina talks about a thing, say a bear, that belongs to her, she says “mine bear”. If it belongs to me, she’ll (correctly) say “your bear”.

But here’s the interesting thing. If she’s talking about several bears, she’ll say “mines bears” and “yours bears”.

She came up with this rule on her own, as far as we can tell.

(I don’t think she ever uses third-person possessives like “his” or “her”.)