I hope I don't offend here but this situation impacts you as much as it affects your partner. Why is it reasonable that you are not allowed to be a part of the discussions as to why this must be done and how bad their financial situation is. If my husband told me that I would be financing his...
Sounds like you are financing your sister in law rather than helping your inlaws out.
If its financial assistance they require why don't you suggest they sell the house on the open market and they find a suitable home to rent. You can then pay their rent. It won't affect your serviceability...
