I have question regarding op-up order

Assuming an SL travels in PE and all DMs, GOs, OWE and OWS in the original PE cabin have been op-up to J ahead of him. Prior to flight departure, assuming that a DM has been op-up from Y to PE, will the op-up DM trump the SL in the event there was another slot for op-up that open up, or will the SL be the next in line for op-up?