I think you may have come to the wrong place looking for advice on patriarchal traditions, other than empathy. MDC does have its limits ;-).
My grandparents willed land to my brother and I. My uncle, with no children that he parented, had use of it till he died. My grandparents were very smart in this. My uncle would have most likely lost it if it wasn't protected. If FIL doesn't state who it goes to next do what you want with it.