I personally think that you're going to complicate your life by doing breakfast. It sounds like a lot to take on. I would be more inclined to break up the free-play somehow. After a certain amount of time, gather them together for something as simple as colouring. You still don't have to be super-involved....but it will break it up. There are always phases like this....I would be firm with discipling their actions as oppose to reworking everything else.
If you change snack time, I'd still keep it simple. Don't go cooking up a storm, just because they can't share. That's just my 2 cents.
At one point I did breakfast for 2 that arrived early (plus my 2 kids) I will NEVER do it again. I didn't realize it at the time, but it's tough. I thought make toast for 2 or 4...what's the difference...but somehow there is one! I guess my coffee just hadn't had time to kick in yet
Now, with preparing my kids breakfasts and lunches for school...never again. If they arrive early, they need full tummies to play nicely while I do my morning routine.