dear friend, never say never, if I think about how much I changed, in my teen years I wasn't just indifferent, I hated christianity, I hated the church with passion.. and still, now I'm here, typing this.. nothing is impossible to God, and God WANTS to save us, God wants to save your family, he will do everything he can, respecting their will..
what you can do, is living your faith with coherence and devotion in order to offer the best example as possible, do it in a natural way, you don't have to show off.. but you can believe that, a good example is the best thing we can give.. you can inspire person, maybe some member of your family could being to have curiosity, ask question, that's how it starts.. plus when you live coherently the christian faith, you will have such an incredible joy, no matter what happens, even in bad circumstances, your family will notice this.. also, obviously, pray for them
these were the general advices I can give you.
if you are catholic consider this:
remain in a state of grace, so you can be within the Communion of the Saints (this is very important)
in general entrust your family to the Holy Virgin's intercession, in particular consecrate your rosaries to their conversion
God Mode: add sacrifices, fasting to your prayers as an offer for their conversion
don't worry, most of the job will be done by God, that I repeat, wants to save them.. you just need to open their ears.. because when God calls (like when he called me) hardly you can resits, but they must be able to hear him.
sorry for the english but you should be able to understand what I want to mean
God bless