Hi Glenn,
I think there would be two basic approaches here but they may not get you into multifamily immediately. Real estate is a long-term game after all. You are going to need to pull equity out to start building a portfolio. Since you are going to be living in one, househack the one with the least amount of equity. Fill the other rooms with roommates and use their rent to help pay the mortgage. For the other property, preferably the one with the most equity:
1) Cash out refinance. You can put tenants in the property and get a DSCR loan pulling out equity. I think your biggest hurdle would be speed as these typically have seasoning requirements. How long you own the property and if your parent will stay on title. With a cash-out, you can keep building wealth and go after another property to add to the portfolio.
2) Sell. This will be the way to pull out the most equity but you lose the property and need to have somewhere to put the money into.
Hope this gives a good starting point!