As far as I know there is no way to merge dives on the OSTC2. Once you have downloaded your dives to your favourite dive logging software on your PC you'll probably have the opportunity to merge two dives with a very short surface interval between them. I know that Subsurface performs this task with ease.
Alternatively you can extend the surface mode switch threshold by upping CF02 to 600 seconds (10 minutes). The side effect of doing this is to postpone the reporting of the start of the surface interval to 10 minutes after you surface from your dive. (If CF02 is set to 0:00 there is no surfacing switch delay and the surface interval reports the actual time since surfacing.)
Sorry to resurrect an old thread, but has the 'solution' to this changed? Is there a way to delete a single dive now?
I'd like to be able to delete one of my dives from the logbook - an aborted dive minute training dive.