Sunshine > Legacy Relationship Records > Query by target

Im using the Custom Data > Legacy Relationship Records objects for a variety of applications, both internal and external. Creating an object + relationship records with this pattern isn't too bad, but when I want to delete a child object, It becomes tedious, there isn't a good way of getting all the relationships belonging to a single object.

The documentation gives the solution to use /api/sunshine/{source_id}/relationships/relationship_type to grab all the relationships that the source object is related to. This is great an all, but I could have several objects related to the same source. Or inversely, my object could be the bottom most object in the tree. 

It would be nice if the api had a url parameter like /sunshine/relationships/records?target=... 
and /sunshine/relationships/records?source=...