Choose the "New FP" option instead of "Update FP" option when searching. As if you're starting from scratch. It'll have you pick the member(s) of your group you want to search for, the date and the park you want to check. Then it'll show all available ride/show listings. If 7DMT is available you can select it and the other 2 you want to chose (including Space and Splash again). Then, it'll give you the best options to choose from (it will ask if you are sure you want to change your reservations but you aren't yet changing them until you click "accept/save" on the final screen so you're safe to search). You can go through the screens up to that point and still be able to click "cancel" and not accept them if you dont' like any of the times given to you. It will only give you up to the 4 best options, so it still may not have your ideal 7DMT time listed, but it at least gives you all available times for it (and doesn't factor in the current FP times you have saved while it searches). Again, it won't clear out your current FP times until you click accept so if you don't like what it shows you then you can cancel.
I've searched this way numerous times and it always saves my FP reservations as long as I don't click accept on the final screen.
Happy hunting!