Ok let's see if I can explain, assuming I understand what you're trying to do.

When you select "change experience" and then select A&E, you'll see the names of the five people assigned to your current "experience" aka attraction, with the green check marks next to their names. Try de-selecting 2 or 3 of the names (click on 2 or 3 of the green check marks as if you're NOT going to change those 2 or 3), leaving the remaining names still with green check marks, and then select the drop down menu with the available times to see if more options open up. If they do, select to accept the change for the names of those you left checked on in green.
Then, go back in again for those 2 or 3 people that you originally de-selected - they should still be under the original experience, select "change experience" for those three, select A&E , and see if you can get overlapping times.
You run the risk of not getting A&E for those names and they'll be left with the original attraction. But you can keep checking back. Also check the FP+ cancellation threads to see if anyone is giving up A&E for your day, and you could coordinate their canceling, and your selecting A&E with them.
Good luck!