Control RTCM INJECTION

Hello,
Is there a way to control which port from pixhawk receives the rtk corrections from mission planner?I have a setup which is using moving base and moving rover and I wanted to send rtk corrections.

Only the moving rover is connected to pixhawk, while receiving heading from a direct connection from moving base. From what I talked with the manufacturer, if I tried to inject corrections from mission into the connection between the moving rover and pixhawk , the corrections moving base---->moving rover and the corrections pixhawk-------->moving rover-------->moving base would collide.

Then he advised me to connect both the moving rover and moving base to pixhawk to that the moving base could also pass the corrections from misssion planner. But wouldn’t that mean that it would send corrections to both moving rover and base and the same collision problem would occur?

So that’s why I asking if there is a way to control which port receives rtk injection, because I think both would receive them, but I am not certain