Duplex options, please share your advice.

[Mike Miguel]

Hey all! New user here. Looking to find some direction on this subject. My family bought a duplex years ago with a friend. 2 units 2 families, both head of families owners on the title. The one family wants to sell, mine however does not. The other family has a real estate agent that is giving us the option to buy the entire property. Is this only option? One real estate agent that I talked to said I may be able to refinance it that way I would owe the original value of the home and not the current value, I would like this option as the home has appreciated quite a bit and I wouldnt want to buy when it is high. Any advice is appreciated, thanks.