Direction notice advising MR of previous decision to that under appeal

Decsision made in 2017, SR care and 4 points on MC. 
Review in 2018 , 0 points on MC, ER DLC.  Client appealed
Client has come to us after recent adjourned hearing with direction notice advising potential to lose ER DLC but to request late MR of original mobility decision in 2017, if not successful and client then appeals both cases would be heard togehter.
Can’t quite get my head round this one. I know the 2018 (superseding) decision is the one under appeal but why can’t the tribunal simply consider grounds for MC at this stage.  The risk in losing ER DLC won’t go irrespective of whether we end up with 2 linked appeals or not.
Haven’t yet seen client to establish strength of case for either component.
Am I missing something?

Does sound odd. Surely they are too late for any grounds MR of a 2017 decision, even if made right at the end of 2017 that is over 13 months ago now.