My Mum had Alzheimer's & recently passed away. In 2006 my mum & step dad made mirror wills leaving everything to each other. They later decided to change their Wills to leave their estates to their own children. However, when solicitor visited she deemed mum did not have capacity to make a new will but she went ahead & made a new one for my step dad. Mum has now passed away but upshot is everything goes to step dad & on his death to his children. Mum would be horrified that me & my brother are effectively cut out. Step dad is losing capacity & refuses to make changes & of course his children support him. Is there any way I can challenge this?