I think that the daughter in law is only obligated to support seniors for <10years while they do not need too much care and attention, the same time seniors might be able to help with some house work.
My opinion is that talking to them about what the daughter in law is obliged to(son can not talk about this due to blood relationship), then give them the chance to make their decision now, of course take the consequence they may facing(after 10 years, the daughter in law have the right to knick them out regardless of this house).
My opinion is that talking to them about what the daughter in law is obliged to(son can not talk about this due to blood relationship), then give them the chance to make their decision now, of course take the consequence they may facing(after 10 years, the daughter in law have the right to knick them out regardless of this house).