I haven't worked with the revit-risa link much myself. However I believe in order to be able to go back and forth and have the link auto-update the model it requires that the specific file that was exported from revit to risa, is then only worked on in risa until exported back to revit. And vice versa. You can't have someone working on the revit model and the risa model simultaneously. Or at least that's how it's been explained to me.
So generally we use revit to export the original model file to Risa, and then we work in separate models and indicate changes the old fashioned way with markups.