SIL's son is married to a woman who has two (now grown up) children from a previous relationship.
She's trying to work out how to gift/bequeath money to her son in a way that his wife and step children don't inherit/benefit should he subsequently die before his wife.
Apart from an expensive/complicated trust it's not possible is it?
She's obsessed by "blood relations" and dislikes her DIL. It's all very unsavoury and I wish she'd leave me out of it.