In most states, a person leaving real property (unimproved land, land with buildings, etc.) can give it to a person as a “life estate”, which has most of the features of outright ownership, EXCEPT that when that gift recipient dies, ownership of the estate is automatically transferred to another.
So, in your situation, you could be given a life estate in the house by your mom, with your nieces & nephews as the next beneficiaries in line. So when you die, it would automatically go to them, bypassing both YOUR estate and that of your sister.
Real estate transactions are definitely one where the best plan is ALWAYS to involve a local lawyer, at least for an initial consultation. If nothing else, they can keep you from messing things up in an irrevocable fashion.