This is definitely possible. I run a Madiface Pro as desktop interface for the DAW and love its usability, relative simplicity (e.g. only 4 analog inputs, you don’t have to search far for the MADI channels), small size and style. It is connected via MADI to a UFX+ which sits in the studio, mainly as preamp and powerful I/O device (it has its own host PC to be fully remote controllable via TotalMix Remote). Great combo, I just love it.

I don’t know if the A16 has Coax MADI in/out - if yes, IMO this would be the easiest way: to switch to a Coax connection between A16 and UFX+, then within the UFX+ route the desired MADI ins from the A16 to MADI outs and vice versa, let the UFX+ run in standalone mode, and from then on use MADI Optical directly between Madiface Pro and UFX+ for access to all combined MADI i/o of A16 and UFX+.
If your UFX+ and A16 can only be connected via MADI optical, you can arrange all three devices in an optical bus (or ring) structure, which also works fine. I just found it to be more prone to human error, as the whole network relies on every single element‘s config to run as intended. ramses in the forum here has heaps of examples and advice on that, just look for his posts.

If you need special info and experience about the combo of Madiface and UFX, feel free to send a direct forum mail. Best wishes.