FWIW, I was told sBs was formed because BWP would not recognize the NA 70DT. I don't know what that means as far as reciprocity between sBs and BWP, but I would assume there would be some limitations due to BWP not accepting results from the NA 70DT. Ronda Stavisky of Rising Star Farm would probably be able to fill you in.
The requirements for stallion licensure are different between the registries here in the us and based on that BWP-NAD and sBs do not have reciprocity as they do in Belgium. Hope that helps with the confusion.