We need more info to go on to provide assistance but yes Rhino geometry and Grasshopper geometry are two separate things.
If you want to use Rhino geometry as your “control” geometry and then have functions happen to said geometry inside of Grasshopper you need to reference the Rhino geometry into Grasshopper, apply said functions, and then bake the resulting modified geometry back into Rhino to complete.
There are MANY ways to reference geometry, here’s a couple getting started guides on different methods:
Thank you so much, hadn’t had the time to test these methods but it’s the solution, just got to learn grasshopper more in general but now I can link both.