Situation: I checked the calendar for all GAPs weekends throughout the summer and signed up for the 3 peaks challenge knowing that it wouldn't overlap. I'm really keen to do the 3 peaks, it's an opportunity that I doubt I'm going to have again and I am really keen to get it done. However... Tuesday evening I get into TAC, OC presents me with a revised calendar that now puts GAP4 and 3 Peaks on the same weekend. I'm torn between the two since I'm trying to join the Marines and I've been told that I am looking at a September date to get to CTCRM (On completion of the selection course). I think both the 3 peaks AND completing my GAP would both be beneficial before starting in September, however this is the only chance I'll get to do either. What is the possibility of doing my GAP training with another regiment/brigade - is this common or doable?