I like the idea to use the relationship_concept_id as a mechanism to identify provenance. Right now we don’t have that. All relationships are the same, whether we import them or create them de-novo. It’s burried in the Pallas vocabulary building system.
The relationship_concept_id you see there is just a concept placeholder for the relationship_id. For example “Maps to” corresponds to 44818977. Why do we need that? To support an information model that graph databases can use for navigation. All entities in the Standardized Vocabularies have an equivalent in the CONCEPT table. However, nobody has done anything with it yet, even though such semantic web / non-SQL / graph database / information model concepts are being brought up regularly.