Why don't you ask your auntie to sell you "an interest" in the house? ....
Even with very best intentions all round, I would stay a million miles away from an arrangement like that.
Considerations such as the following would support my thinking:
- the true value of the property and what might be an appropriate payment for "part" of the house now, what the future price of the remainder of the house might be (if not left in a future will), what happens if the "tenants" cannot pay the remainder at some future point in time when the aunt needs further funds perhaps.
- who else might have a vested interest in the house (directly, or indirectly) and object to an initial arrangement, or later come back and challenge the arrangement through the courts, perhaps claiming the aunt was taken advantage of in some manner etc.
- risk of later dispute between the aunt and "tenants" leading to daily difficulties on trival matters or worse yet, a full scale legal battle if things got completely out of hand, who pays what percentage of the property tax, water bills etc.
....The list goes on and on.