Question on exclusive rights to a property left to us for someone living inside the property?

My father recently passed away, his will says he leaves everything to my sister and I 50/50. We have a couple of properties we will sell but we also have a third property where my grandmother lives. For this property he modified his will for it to say: Specific Bequest: I give, devise and bequeath to my mother {mothers_name), the absolute and exclusive rights to use during her lifetime (property_address}. My estate shall be responsible for property taxes, insurance, utilities and maintenance, {mothers_name} shall live there expense free. My question is will money we make from selling the last 2 remaining properties be held from us until my fathers mother passes away? Or can we settle this outside of the estate by opening some sort of trust fund where some money is placed in the trust fund? It seems a strange way to ensure that my grandmother lives there but it seems as if the property title will go to my sister and I? Thank you