Years ago when the M∴P∴G∴C∴ visited our L. in NYC, she addressed us on L. protocol, one point of which was that the chairs of the RWM and Wardens should never be vacant under any circumstance.
Whenever one of those officers leaves his/her place, the substitute is drawn into the chair from the left with the grip of the degree and the officer exits on the right. I can't remember how the IPM, who is stationed at the right of the RWM, could be drawn in from the left without some fancy shuffling.
Is this protocol observed in your LL? What are the logistics for getting the IPM into the chair of the RWM whenever that officer descends to the floor of the L? Or are we putting too fine a point on the matter?
There are various practices, for example the Wardens when leaving their pedestals may take their columns with them and hold them while working on the floor - except in the dark half of the 3rd degree.
In the Golden Dawn when the Wardens stepped on to the floor the brethren were supposed to visual the Wardens (in the form of Egyptian gods) still being in their places.
As for moving the IPM, it is possible for the RWM to stand and hold the hand of the IPM who then walks around the front of the Master's pedestal and into the Master's chair through the North - all holding the hand of the Master. That process seems to work without disturbing the energies. I am not sure I have seen that in a ritual but I had the RWM do it at practice and it went easily.