DUDE that worked, but here's a couple of notes for anyone else that runs into this. The "Collector tool" goes on the "inside" model that contains the iterator, BUT the Output of the Collector is flaged as a parameter for the "outer model". ALSO, I banged my head against a wall for 30 minutes because modelbuilder flagged the input tables into the collector as intermediate, and thus was deleting them right before the merge tool fired off!! Uncheck that box for this exercise. 🙂
Thank you so much!