Add Part Plant Records (Service Connect or ABL)

We have 4 plants with a common set of purchased parts. I'm looking for a method to add part plant records for all the plants for all new and all existing parts. My thought is to either use service connect or through ABL code but I have the following issues:

Service Connect: It's easy enough to call the BO to add the plant record, but I can't come up with a way to find Parts where the part plant record doesn't exist. If I could find the missing part plant records I would run a scheduled task to find a part with a missing part plant record then add the record.

ABL code: I can write ABL code to test if the part plant doesn't exists, but I'm not sure how to add the part plant record.

Any thoughts?

Thanks for any help and I'm make sure I post my finished solution.