Need help combining chicks

[Mel281]

So I have five chicks that are 3 1/2 weeks old. I have three chicks that are about four days old. I need some advice on how to put them together. I did OK at first, but then I noticed the little ones all huddled into a corner all the big ones had free reign of whatever they wanted. I have two of everything – heating pads, water, food. I have a current set up with a divider that allows the little chicks to go back and forth but the big ones can’t get to them when the littles are on “their” side. The babies pretty much always stay on their side.
The problem is, I don’t know that they’re ever going to get used to each other like this. They don’t seem to be especially brutal to the small ones, but just pushing them away and resource hogging.
And right now the set up only the works for during the day because it is not predator proof. I have to separate at night.
How can I get them together without putting the little ones at risk?

 

[Mel281]

This is where the older chicks sleep at night and I don’t know if it’s safe to put the babies in their with them at night. I don’t know that it’s big enough for two sets of food, water, and heating pads and 8 birds.

 

[sourland]

I'd give them more time and keep them separate at night. The size difference between 4 day olds and the larger chicks is too great. Give them another week or two just as you are presently doing. I think you'll see more integration as the younger chicks grow.

 

[CannedMonster]

I'd give them more time and keep them separate at night. The size difference between 4 day olds and the larger chicks is too great. Give them another week or two just as you are presently doing. I think you'll see more integration as the younger chicks grow.

Exactly what Sourland said.
I would add that as long as they can see each other throughout the day, through the fence, they will get used to each other until the younger ones catch up more in size.
I’ve noticed that once chicks are fully feathered they get a growth spurt.
Perhaps putting each sides food/water next to the fence will facilitate interaction.