Massallah pertaining to inheritance

my brother in law , took a piece of land that we had verbally agreed to share and share profits 60/40 he subsequesntly registered the property on his name and then told me i must bugger off as i have nothing to do with the property etc,is this theft?
then he took all the inheritance from my wife and her sisters ..he said his father had given him everything
my children who i am sure were left some thing by their grandfather are now not given anything
debt left by my father in law -do i have to settle the debt as well or does his estate do that.he left a block of flats and huge house?
my sisters have both married out of the deen of islam do they still inherit from my fathers estate …i in doubt with regards to their practise of the deen as both their husbands drink …what is their status in islam