How can I add reference return path via (ground via) in a symmetric way in PCB Editor?
you can

Measure the distance between the two vias you want to place the new via in between.

Make the grid of your pcb editor to 1/2 of this distance.

Mark one of these two vias as &quot;the origin of the axis&quot;.

Finally, put the new via between them. The pcb editor will guide the via to be exactly in the middle.