I look after my 2 year old DGD one day/week. Her little brother was born a fortnight ago and of course DGDs nose is out of joint a little - she's no longer the centre of her known universe! As far as I can see, her parents (my DD and partner) are doing their best to help her overcome this. They are a kind, gentle family and treat DGD with kindness and gentleness.
Anyway, DGD usually enjoys her time here and sometimes says laughingly that she doesn't want to go home when the time comes - but yesterday was different. She didn't want to go home, she started getting upset about it - she wanted to LIVE with me and she definitely didn't want to see her brother (although she agreed she'd like to see Mummy and Daddy).
My heart aches for her, but I know this is par for the course and hopefully everything will settle soon. (I'm a big sister and remember the upset when my sibling was born!) What I can't decide is whether to tell my DD this. DGD was off her food but very cuddly yesterday and I think I'm being blamed a bit for allowing her to "go hungry" so that she got into a bad mood (but I didn't! I was offering all her fav food on a 1/2 hourly basis through the afternoon!) so of course I feel a bit defensive about that, but my feelings are the least important here, I'll cope! We can't send the baby back (!) so DGD will have to learn to
live with the new setup; and I worry that if I tell Mum it will upset her (and her MH is a bit rocky anyway).
If you were her Mum, would you want to know what DGD said?
YABU - just tell her, she should know what her little one said. She's probably said it at home already.
YANBU - don't tell her, nothing can be changed and it might make it worse if Mum feels bad/guilty, as she may well do (knowing her as I do!)