No doubt it's too late to change this, but have you thought about using NewId rather than identity as your (nonclustered) PK in the various tables?
As far as I know, this is guaranteed to be unique across the distributed instances and could therefore become the 'permanent' PK for a row, regardless of database.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.