Hey! Thank you for letting me know. You are completely right; I am not up to speed with creating multi-polygons. I was following this wiki page https://wiki.openstreetmap.org/wiki/Key:building:part#How_to_use and I completely misunderstood what the page was conveying. I've read though your linked wiki page, and others relating to mapping complex areas, and I've reconstructed the building in hopes of correcting this. If you could let me know if I have done so correctly, or if changes still need to be made, I would be most appreciative https://www.openstreetmap.org/changeset/139963990