There is no way to force a device to utilize a specific Sattelite or Root Mesh Router Pro.
This feature has been requested on the Wishlist. Follow the link, vote at the top, like some posts, and add your own post to the topic to support the request.
I have had this issue with several of my cams. Most recently the Floodlight Pro. It seems that cams sometimes get an unhealthy addiction for being connected to the root which is further away and won’t let go.
I have found that power cycling the cam allows it to connect to the best connection. If that doesn’t work or I have several cams off the reservation, a router reboot usually resets the landscape.