You could try using Tonto, it allows you to have multiple ccf's open at the same time. With Prontoedit you're stuck with merge.
There's nothing special about a gallery, it's just a ccf named gallery. Take the ccf you want to use as a gallery and cut everything out that you don't want, organize your buttons/frames and save it as gallery1 or whatever. Just don't overwrite something you want, and don't save your chopped up primary ccf as it's original name.
Jim L