You could always leave the door of the crate open on a night time (assuming the crate is in the shed) - they will decide when they feel safe enough to roost with the rest of the flock. I usually keep new birds for a couple of days in the main coop, and then let them out with the rest of the flock. I reckon when they free range its a lot less stressful as newbies can escape from established flock members. Putting a couple of feeding stations out of sight of each other will also help in reducing squabbles over food.
I introduced 4 new 4.5 month old pullets to my existing flock (6 hens and 8 seven week old chicks) three days ago and the squabbling was minimal and lasted no more than an hour or two - after the new ones knew their place in the pecking order it was fine.
Having said that, you should really do what you feel is best. Supervised free-ranging is a good way to observe the kind of reception your little ones will have. As you have mentioned there was nothing major on your first attempt, so why not increase the duration and frequency of the free ranging? I would not imagine that you would have to be there all the time, as, from what you have said, theres been no crazy fighting and things will only get better.
Theres a lot of threads on introducing new flock members, so be sure to take a squizz at them.
Good luck whatever you decide to do.
CT
