Todd, when are you going to get those fish a bigger tank?
Geaux xman, do you have corals? The yellows may be a bit nipier. Bicolors are not beginner fish. You'd want to read up on them. It used to be really, really hard to find a healthy Herald's in some areas.
There are some prerequisites for combining angels
1) LOTS of
well seasoned live rock stacked loosely with as much surface area as possible exposed. Preferably very little rock touching the back. It should be arranged for lots of hiding areas, swim throughs and visually blocking different areas of the tank. The thought is to allow the fish to avoid each others line of site if they so choose.
2) A willingness to remove a fish if need be which can be a big job.
3) If you're going to go to all that trouble, it makes sense that the fish should be the priority, not the corals.
For the ones you chose, I would add the bicolor first, then the Herald's followed by the flame. If I could, I'd give the bicolor about 3-4 weeks. Then possibly add the Herald and the flame about 3 days apart.
I personally wouldn't put a lemon peel in with the bicolor. That doesn't mean it couldn't work.
It helps if each fish you add is bigger than the existing angel(s).