A: Every client deserves respect. Your sister can have a Revocable Living Trust that specifically divides the home evenly between her son and daughter. How is the daughter blocking your sister's wishes?
A: If you came into the country without documentation you will have to consular process. That means that you will file your spousal petition I-130 then when it gets approved you make an appointment to process through the consulate, e.g. Ciudad Juarez. They will ask for a waiver of your unlawful presence and that could take 9 months to a year. To avoid that, once you have an approve family (spousal ) petition you prepare and file a 601A waiver for the unlawful presence. You will have to show hardship to a qualifying relative (your spouse). You send that off and wait for an answer and when it comes back YES/APPROVED then you make the appointment to consular process. With your waiver you will only be out of the country for a week instead of months. Just make sure there are no other impediments to your receiving lawful permanent residence.