Introducing young chicks to older chicks

[Rachealx4]

My older batch of chicks are somewhere around 5-7 weeks. They are all BO and are currently living in a large modified dog crate. I just got 9 chicks that are less than a week to just a week. They will live in a tote for the time being. Eventually I will merge these two flocks. Should I put their brooder next to each other so that they can see and hear each other now or just wait?
Actually while I'm posting I have one more question. The new flock has black sexlink, silver laced wyandotte and barred rock, 3 of each so far. Any reason why these guys should not be added to my BO flock?
Thank you! I appreciate how helpful you all are!

 

[SueT]

Yes, put them where they can see and hear each other until they are all about the same size. Well, are you moving the elder ones outside now? If so, then divide your coop/run temporarily when the littles are ready to move out. No reason not to mix the breeds together, just have to carefully monitor integration due to size/age differences. They aren't going to be one big happy family right away.

 

[Rachealx4]

@SueT The bigs are going to the garage soon...hopefully this week as we are moving and the coop isn't done. I designed my coop so that it can be divided either temporarily or permanently if needed. I wanted to make sure there were fast and easy options in a pinch.
The littles can gotto the garage with a heat source, correct?

 

[Rachealx4]

The littles can gotto the garage with a heat source, correct?

 

[SueT]

The littles can gotto the garage with a heat source, correct?

Yes!