Have NC and changed a few details as family members read this forum.
I have 2 dc, DD who is 9 and DS who is 4. Before DS was born and after FIL died, my MIL changed her will to split inheritance equally in 4 between DH, his DSis and DB and our DD. MIL stated that if we had any more kids, DD'S share would be split between her and however many more dc's we have.
We are now about 6 years on from that point and it seems MIL has no intention of changing her will to include DS. DH's brother is an executor of the will and he has tried to talk to her about it, only to be fobbed off or told that DS not being included is 'his issue'. MIL does seem to favour DD more than DS, this comes across in her actions in other ways, DD was the only GC for 4 years (BIL and SIL have no kids and don't want any).
I'm getting worried about the effects this may have on our family in the future and how it might all make DS feel. It's not a small amount of money - about 100k DD stands to inherit when she turns 21.
A part of me hopes it will all get blown on care home fees - whenever inheritance threads appear on mn, a large proportion of people mention that the person is unlikely to get their hands on any cash due to the possibility of this. AIBU to hope this is the outcome? None of MILs children would look after her themselves, they all have difficult relationships with her and can only tolerate her in small doses. She is in her 70s and in ok health.