Fairly long back story but will try to keep this short.
DP & I split up 7 years ago, we reconnected 5 years ago and I have 2 DC with him and 1 DC I had whilst we were separated
My youngest DC dad chose to not have any contact and what's nothing to do with him, my ex and his family have been amazing in treating youngest DC like he is one of their own.
However , there is an event taking place in December where MIL is having all the grand children but refuses to have youngest DC - this is a common occurrence and have pretty much been informed by another family this is how it will always be going forward so he will miss out on any trips away she does, sleepovers etc
Whilst I understand he is not related to them by blood, and he s always treated the same on birthdays etc, I don't know if I should stop DC calling them nanny etc because of this exclusion, I have no family myself so this is all DC knows and I don't want him to grow up to think this is normal but I don't know what to say as I am also grateful DC is not excluded on birthdays etc