Contact with birth families.

[HotI]

what are the other kids told now? who do they think is the little one they visit?

If the oldest is now 7, and has younger siblings living with her, she might remember her Mum being pregnant and no baby coming home and may have worked out that your little one is her sibling. Kids are sometimes cluey than they are given credit for.

I was thinking that the other kids might benefit from books on adoption, as a way for their parents to explain to them (if they want to).

My Mum made the 'life book' for my sister 25 years ago. They are used widely now, but back then were not advocated or even talked about. Don't know if hers was the first, but Mum just came up with the idea herself.

I thought hiding adoption and information from your children was long gone.

unfortunately, not always. It depends on the family, and the tools they have to explain things that aren't so common.