I have 4, 1yr old hens, and 11 2-3mth old chicks. Is it better to combine them at this age or wait? Do they have a harder time if they're 5-6mths old? They've been free ranging together for some time with very little problems.
If they've been getting along while free ranging, go for it. Just be sure to have several feeding and watering stations and a few obstacles for the little ones to hide in or around. You're going to want a few places where the chicks can get out of the way, or out of the older hens' line of sight.