I think all of you need to sit down now and discuss. Ask the sister in law if she is willing to split expenses and have claim to the house and any inheritance. I am sure she will say no.

Also, talk to an attorney because if you're in laws end up with huge medical bills, how will that affect you, etc.

Are you getting the mortgage, going to be on the mortgage? If they don't pay, it can affect your credit.

Is there a reason they want to cut your sister in law out of the will? I know 2 families that did that. In both of them the siblings never talked again

I'm confused why you even need to be involved in any of these deals. It doesn't sound like you are living with them

My husband was offered considerably more but in a small industry that he would be burning large bridges moving in.

If your new boss passes tomorrow, will it be hard to find a similar paying job? If the answer is no, then go where you are happy.

How hard is it to get a job in your field?