Grandparents left mortgage to Estate - Estate wants to sign to me

[Russell Moran]

My grandparents passed away last year. I am the oldest grandchild. My mom and aunt are the only 2 surviving children of my grandparents. Grandparents had a will and my aunt moved into the house and taking over payments in agreement from both children (her and my mom). She is moving out of the house and does not want the payments anymore and wants the house to stay in the family. She wants me (the oldest and financial advisor) to assume the payments. My mom and aunt will sign over the house to me from the "estate" which they are over. My goal is to take over the house and "OWN" it, not just pay the bank for it. I will be renting it out to other family members to help them out. I am reading I can't "assume" the mortgage, but rather I'd have to get a new mortgage. Since this is rental property I would have to traditional come up with 20% down in TX. What's the cheapest way to legally take possession of this property?