Today while loading 1,500 lbs of diapers and baby food onto our Citation II, I quickly realized there was going to be 3 palates of cargo that I couldn't fit on the run. I noticed a Shorts 360 freighter on the ramp at OPF taking on a few palates of aid from La Colonia, a Miami area medical center. I approached the group and asked if they could spare any room. The pilot ran some numbers and advised me that he could get another 700 LBS of cargo onto the aircraft! We got the aircraft loaded with more diapers, water, and food which was flown into San Juan that day and distributed along with their supplies!