can i put 4 week old chicks with 1 and a half week old chicks ?

If they are about the same size I would see no problem with it except that if they came from some where else then they need to be separate from all other groups.

 

Well I, I am new, but I am into easy. It doesn't work for me to have to fuss over my flock too much. So I would put them together with some type of separator between them until they get used to it and I would think they would get along fine. I have two groups 2 weeks apart. They were raised in the same coop for the first 2 weeks and then they were just let out together. The mom's were my problem. Now all 14 do everything together. I would be extra careful with yours just to make sure the size difference doesn't result in the big ones picking on the others.

I am getting 4 silkies soon. My plan is to put them in the booding coop for about a week and then after that let them out to free range with everyone else and see how it goes.