Spoon each variety of potato onto separate large sheet of heavy-duty foil. Drizzle with oil; toss potatoes until evenly coated with oil. Fold foil to make 3 packets.
Grill Yukon gold and red potato packets 10 min. Add sweet potato packet to barbecue and grill all for another 10 min. Turn all packets over; grill 10 min. more or until potatoes are tender.
Empty packets into large bowl. Add Cooking Creme; toss to evenly coat. Stir in onions.
Variation: Potatoes can be cooked on the stove top instead of on the barbecue. Add whole Yukon gold and red potatoes to saucepan of boiling water; cook 25 to 30 min. or just until potatoes are tender. Meanwhile, cook cubed peeled sweet potatoes in separate saucepan of boiling water 15 to 20 min. or just until tender. Drain potatoes. Cut whole potatoes into 1-inch pieces, then prepare recipe as directed.