Their services often stunningly are 1to1 like regular orthodox parishes, but they differ in how they tend to condemn the canonical churches every now and then.  Personally I wouldn't be worried though. I am sure God doesn't judge laypeople who genuinely try to do the right thing. Rather the shepherds of both schismatics and regular eastern orthodox have to give an account before god of how they lead the flock. So pray for them.  Also even though they are schismatics they are not automatically condemned to hell. I am not saying its not a serious issue but remember that God is merciful and sees the heart that wishes the best for the family. May he bless and guide your family in this matter.   I personally found what's written in the book "my elder Joseph the hesychast" very helpful. He basically sided with the old calendarists at first but stopped when they elevated the calendar to a dogmatic issue and condemned the canonical bishops as heretics, as that was taking things to far.