To cut a long story short, my DP's family are a bit manic and almost living in their own worlds entirely. I had my son last year, his birthday is fast approaching. I've planned a party for him (over the top, I know but life is short) and have invited all of our families.
As expected, my SIL and her sub-family (Close Ex-Partner, Son & Girlfriend, Daughter & her own partner) are busy. I have absolutely no problem with this however we initially mentioned about hosting a gathering at our house and my MIL told her she wouldn't be invited (this was months ago) because her and her own family do not like our dog and it's not fair for our dog to be shut away when he gets on with everyone else. She kicked off, made a few unnecessary comments about how it isn't "fair" and so forth. So, we told her we'd plan to host in a neutral location, without the dog. Gave her several weeks notice and have found out she's busy. Oh well.
However, she has seen my son about 3-4 times over the year. She didn't start making an effort until we invited her to his birthday and she said she couldn't come. She's now saying we should plan something with her own children, partner etc. for my son's birthday. I don't really want to - she never made an effort before, her and my DP are not close and, again, I can count on one hand how many times she has seen him over the year since he was born. She has no money, so we'd have to pay for whatever she is suggesting and also, I know this sounds awful but why should i go to the effort of planning something just for them when I've already spent months arranging this party anyway?