Generally speaking, a lease is an agreement to rent/occupy land or a building or a house from another for a period of time in exchange for the occupants paying rent. The best solution would be to have your mother contact an attorney to draft a lease and get all parties occupying the house to sign it. Once signed by all parties, the lease would then be the agreement for everyone to pay rent on time, etc. A lease would also spell-out the remedies should someone not pay rent, etc. Please note, an attorney should be consulted in this situation because it is a sensitive situation. The current terms orally agreed upon need to be consolidated into the lease that is drafted and singed and new terms which protect your mother also need to be negotiated and drafted into the lease that is signed. Additionally, Some cities have ordinances or building codes which restrict the number of occupants in the home, a violation of which could result in a penalty to your mother. Again, an attorney can assist you with all of these complex issues.