One approach in these situations is to make a Sync table called parking Lot Sync in the same app to mirror the Parking lots table and then change the key field of that table to the Lot# as I assume it is Unique.
Then you can relate the catch basins to that Parking Lot Sync table. That may be enough to solve your issue, but if you really do need to have them attached by a Relationship, then you can make a relationship between Parking Lot Sync to many Parking lots and then do a summary maximum of the [Record ID#] field can call it [Record ID# of parking lot].
Then look that up down to Catch basis and use that for your relation to Parking Lots.
