princessparty- I did say that I am aware that I don't own any name but I am annoyed that my dd and my dn do share the same surname and they have chosen the same nickname. Had it been a different surname, had they chosen a different nickname, had they been living far apart not seeing each other often, I don't think I would be too bothered.
Cantspel- you're right, it IS a popular name/nickname and as a teacher I have had lots of little Belles and Bellas in my class but to have the same surname and to potentially be in the same class when they go to school (live in same catchment as BIL & SIL), is why I have an issue with it being so similar. It just isn't sitting comfortably with me.
ib- it isn't "rare" family occasions- they are together every week at least once and often DN comes to play at our house. I hope newest DN will be the same and so it isn't rare, they will be spending time together weekly at the least.
Bendybob- I hope they won't continue to do this with other children! They already have a DD whose name is nothing like any of my daughters and is quite a different style to Isabelle actually which is why I was shocked also when they announced the name.
Pink4ever- I'm not sure if she has done it to spite me. I hope not :( She has always been sort of distant towards me but she is the same to everyone else in the family so it isn't that she has a particular gripe with me. She's happy to leave her DD with me relatively often, but more often than not BIL will do the dropping off/arranging/picking up. I was very close to BILs ex fiancee (no children together) and I am still in contact with her as she became a friend. MIL is very bitter that BIL "let ex fiancee go" as, as I said, she isn't too fond of SIL. This is the only thing I can think of that she would have an issue with with me. :( I try my best to make her welcome into the family and always invite BIL & SIL over with DN for birthdays etc. She doesn't always accept but I do always ask. Not sure why she would have such a grudge against me if she has done this intentionally, as you suggest she could have :(
I sort of wish she had spoken to me about the name and actually, if she had and she told me she loved it then of course, I couldn't have said, "no, don't use it". I would have suggested/encouraged a different nickname or a different middle name but I know I don't own the name so I couldn't have said "no, you're not using it". It's the fact she has just gone ahead, done this and not mentioned it!
Thank you all- you're all so lovely. Felt so alone in this until I posted here- so glad I did. :)