Mixed flock (on every possible level)--brooding together, bad idea?

[prepperchickens]

We have a mixed flock of 5 chicks. The eldest is our 4.5 week old Ameracuana (?) pullet, then our two 3 week old guinea hen keets, all 3 of whom were bought together a month ago. About 9 says ago we bought 2 barred rock chicks each 3 days old, both were supposed to be female but alas, ones a roo. We didn't know any better so we put the 2 chicks in with the older birds the first night and it wasn't until the next day I realized their temperature needs were different and that I may need to keep a close eye on them so I made a small brooder for my room to keep them in at night when it gets cooler and I'm not supervising them. But during the day they'd be with the older birds and as of last night I've begun leaving them in there at night also. The guineas are so gentle and kind natured they let the tiny chicks push them around, my Amerecuana pecked them a little the first day but we scolded her and it hasn't happened since!! My question is, though, if they're barely 2 weeks old is it too soon to leave them with the big birds around the clock? Could there be risks I'm not considering? My roo is the runt, he was the runt at the store too, but he's very assertive and seems to have no trouble fending for himself but I am brand new at chickens and I don't want to take chances. It's just the chicks seem so happy with the big birds I feel bad taking them away at night. I have put multiple levels in the brooder to allow the tiny chicks to get closer to the heat lamp if they need while the older birds can stay farther away. Here's a photo of the little flock for perspective. I would appreciate anyone's thoughts on the matter

 

[ChickensAreSweet]

In general I don't mix day olds with anyone older than two weeks older.

I always feel that once a flock is integrated they should stay integrated. But maybe you can put them in a larger container so the larger ones can get away from the heat? This is an issue that will be around for several weeks and the big ones will just keep getting bigger. I am assuming that you are removing the smaller ones for temperature control?

Of course there is always the risk for bullying in the middle of the night and injuries. If you have already integrated them with no injuries though I don't know what to tell you- maybe they will be OK and maybe not.

I hope this helps!