Rent

My father-in-law died in July of this year and my husband's sister is exeutor. She and her family have been living there since there dad died. They already have a house of their own to live in,it is a rental as far as I know. What is everyone's opinion that they should be paying rent to the estate while they are living there at their dad's house? There is no reason for them to stay there since the other sister and her husband live right next door and can watch the house just as easy. She,the executor,is taking advantage of everything that she can. My youngest sister-in-law got another attorney involved and was able to get her court supervised for the estate. Hope everyone can figure out what I am trying to ask. They are living on 13+ acres and I feel that they should pay rent of at least $1500/month. That is cheap compared to what I have seen other places. I have nothing against her except that she isn't following to the letter what their dad asked in the will. I know that I am the in-law but the other siblings need a lot of encouragement.

Thanks in advance for any reply to this.