Nope you can't combine paid and award on the same PNR. It will require two transactions. You'd have one for the paid and one for the award (assuming you'll buy both paid tickets and then the 3 award together)

Best bet is to call and have a note put in the PNRs linking/cross-referencing them and ask the agent if they can put them in EC also since its a family vacation and because you aren't able to do it all at once with award and paid tix.