Am i over reacting?

I have 13 nieces and 1 nephew ,my eldest nieces are 7 and 5 years older than the rest so obviously they were very spoilt by all of us when they were first born, since the rest of the mob have come along my SIL (thier Mum) is so obviously jealous everytime a new baby is born into the family, she even starts ridiculous arguements about us not seeing her children often enough. Yesterday we had a family lunch at my parents house and 7 over the kids were there including my daughter (who both my brothers and SIL's have only seen about 5 times in 7 months). Now my SIL payed NO attention to my daughter AT all never held her, played with her and the only time she ackowleged her was when she wanted to take photo's. She constantly complains that i don't see her children anough but she doesn't know i am in contact with her 2 oldest daughters on a weekly basis (they are 16 and 18) i even brought my niece personalised number plates for her 18th. ***cont'd***