I thought about that ie OH keeps kids at home but I felt I've said enough.
People told me at work that I took the practical route to solutions.
As I said, before you give/lend, you need to satisfy yourself: Are they doing enough to help themselves - could they be nudged by someone in the right direction - only then lend/gift amounts
A word of caution: One you start giving money, they may not appreciate it if/when you stop or wrongly start assuming that your every comment is based on them getting themselves into trouble
Does the OH not have parents/family that can also help?
Best way forward - OH looks after their kids - OH considers his future work role and possibly a change. - OH needs to consider that its not an insult to get another job that may pay a lot less - OH needs to consider getting out of the house does help and sis needs to consider this as well - they need to seek a mortgage holiday or increase term and the sooner they speak to lender the better
Do the have any other lending other than the house you are aware of?
Have they actually cut back on anything, tv, mobiles, memberships, downgraded car, sold car if they have more than one - changing food to cheaper brands - it all makes savings?
TBH. I would not help them if they had not been taking action and would only help when they lost their home (Hopefully it will never come to that)
This does not sound great, but I do blame your sister a lot from the info you supplied, EG try to shiled her OH from reality. That is all fine if you have the financial resources but if not, start to cut back
To me, you/OP sound like a very down-to-earth person that is practical like me and must hold a job that you enjoy to a good extent.
Good luck a