Or you could modify your GS pillion hangers to work with the BMW racks by cutting off the lugs but they will then be redundant for use with the Varios
I have a set of GS pillion hangers that some nutter butchered with a hacksaw to get the aluminium pannier frames to fit
I will try and dig them out for a photo
Here you go
He's cut the Vario pannier lug off and didn't make a very good job of neatly finishing it off
If they are of any use to you then you can have them for £25 delivered