Buying new primary, renting out old primary then selling old primary

How should I input the data for this: I plan to buy a new primary home (with a seller's loan with a fixed rate five year balloon using a 30 year monthly payment amortization AND a gift from a brother for part of the down payment AND the remainder of the down payment from my savings/stock sales) and rent out my current primary residence, which I then plan to sell in three years, using the equity to pay off the balloon loan and the no interest "gift" from my brother. There is no provision for entering these three different financing sources with these terms.

I understand I should enter my current primary home as real estate since I will rent it out at the time I purchase the new primary house, but entering the timing is confusing because the house will convert to a rental only when I purchase the new primary.

Nothing I try works. The program won't accept certain of my inputs.

Also, is there a straight forward way yet to input a HELOC (on my current primary) and test several payoff scenarios?

Thanks. Mark Weaver