Yes, they will fully accommodate/customize anything (in my experience). For example, at Razzle Dazzle, I ordered the Waffle entree, but Waffle plain with only syrup on the side...and I added just the chicken filet from the chicken sandwich. So, a classic Nashville Chicken & Waffles. It caught on actually, so I'm surprised they haven't added it to the menu...haha.
At the beginning of every meal they ask about allergies and if you've reported one previously it's saved to your profile and they again validate.