Welcome to FT, lvmil.

It seems to me like you'll need to be able to make two separate bookings, as your miles are in two different programs (SQ's and UA's). You should become familiar with the 'rules' of the individual programs in terms of award costs for your desired destinations, etc. The next step would be to find the possible ways you can get to them on *A, and then make the call to book your awards... At that stage, I'd recommend that you perhaps talk to SQ first and quiz them for routings where *two* seats are available; once you find one, hold that reservation and the immediately call UA and try to get the itinerary replicated.

Good luck.