Since it has been two weeks I'd open the door on the brooder and see what happens. Do it sometimes when you can check on them instead of when you away, like for work. I've had chicks not come out of the brooder until the third day after I open that door, I've had all 20 chicks outside within 15 minutes. Each group is different. I generally do this at 5 weeks of age.
I don't know how your older hens will react. Usually mine ignore the chicks unless they invade the older girls' personal space. If they do that they may get pecked and chased. Usually the younger ones quickly learn to avoid the older. I've never had a chick get injured doing this but you can read some stories on here where people have. It is a good idea to occasionally check on them.
I'm very happy for the chicks to spend the nights in their brooder at first. Once they prove they can get along with the adults without being chased I move them into the main coop, usually at around 12 weeks old. My 8' x 12' coop is big enough that the chicks can stay away from the adults. The chicks do not sleep on the main roosts with the adults but stay in a separate area. I do this so often I put in a juvenile roost, lower than the adult roost, higher than the nests, and separated horizontally from the adult roost buy about 3 feet. Once the chicks are ready to roost they move onto that juvenile roost on their own. Until then they sleep on the coop floor in a far corner. When they are ready they move themselves to the main roosts with the adults. That's typically when the pullets start to lay.
