[Freeswitch-users] move people from a passthrough conference to a mux conference

Hello, I am investigating the traditional use case where a one to one call starts as relay mode (conference passthrough), and goes mcu when adding a third person in the call. I would like to do it server side only, and transparent for the clients. That means freeswitch would move the one to one call to a mux conference, and then the third guy would join the mcu conference. Is it something possible in freeswitch? what would be the cli commands or modules to use to do this? regards, Jean