[CQ-Contest] MS Question

[Roger Huntley]

The run station (0) is on 15 running and the mult station (1) is on 20
picking off mults.  Both stations have been on their respective bands for
over 10 minutes.  My question is can the mult station (1) continue on 20 but
now is running stations working any and all.  The run station (0) stays on
15 now just working mults?  Can either station be the run station or do you
have to designate one of the stations as the run station and have him stay
as the run station throughout the contest?
Thanks,
Roger, W7VV