To my knowledge, there is no way for non-staff to query the database for places created by a particular user. You also can’t share or transfer “ownership” of a place.
You can use the API to find places that contain a particular lat/lon, or that are within a particular bounding box (also possible using the Explore map), but you can’t find places that intersect with another place.
If you’d like to see some of these implemented, please submit a feature request.