nm, be firm and assertive. She has to contribute too. She might be an heir to the land, but she hasn't contributed ANYTHING yet, and the "promise" of land doesn't mean a damn thing. She needs to start contributing now. As my mom always said, "Them that works, eats."

And didn't you mention that there were siblings of your wife that your MIL expected you to take care of as well when TSHTF? If they aren't going to contribute and Mom wants to include them too, guess what, she needs to contribute for THEIR needs.