Labelling/referencing of Pillboxes

I am working on details on the Kennet and Avon canal here in Berkshire, Wiltshire and Sommerset. It is festooned with pillboxes as an obvious defence, and so I’m trying to mark them as buildings where I see them. There has been some excellent work done by the Archaeology Data Service as part of the Defence of Britain project, and these pillboxes actually have reference numbers (there may have even been an upload of the location data held there as many of the pillboxes have points in the map already) .
It might be useful to add a key “reference_number” or similar to the objects, giving the ADS reference, but I’m not sure if this kind of external referencing is “the done thing”. Should I propose something, if so where ?. I’m as much interested in the “legal process” of how we decide on this stuff as my actual suggestion.

Note, I have NO intention of doing this with an upload, I’m just interested in manually getting the Kennet and Avon as well mapped as possible. The fortification of the canal in 1940/41 is obviously an important aspect of it’s history.