We've had a few customers ask if we could create a transition where different amounts of straight can be entered for each side. Instead of using a transition, use another fitting created just for that purpose, either the Right or Left Facing Double Radius Entered Offsets (fittings #182 & 185). Enter different amounts of straight on each side of the fitting (see red arrows), but keep the radius's set to 0.00 to make the duct square.