Personally, just install a dedicated Mythbox no logins boot and go. I've set one up for my Grandmother, Mom and both my sisters. My mom and sisters are computer literate, my Grandmother for get it. All machines work well, why complicate things when you don't need to. I really feel your gonna end up being a full time support rep. I don't see my family enough and would rather not talk to them about stupid computer related stuff.