Morticia,
I can't begin to tell you how much I admire your courage. This model does not come with an instruction manual. A lot depends on how much of a relationship you had with him before he lost his father. And he is grieving which will probably take the form of anger. Listen a lot. And get professional advice when you feel you need it. At fifteen, he is eager to be independent and just as eager to be controlled. You can't win.
Love works and listen if and when he does something other than grunt.
PM me if you want specifics - been there and done that. It is worth the effort.
SINS