So, getting back to the part about being in with large fowl, I would say that if your other large fowl are already a week/two weeks old, the earlier you combine your chicks together, the better.
I have successfully combined two-week old chicks with day olds. But a three week difference was too much and I had to wait until the younger group was around one months old to combine them with the seven-week olds.
So, if you cannot put your silkie chicks in right now with your others, you will definitely need a separate brooding space for them. When you combine your flocks later, I'd take one brown egg layer out and put her with the silkies for awhile. Then they will be friends hopefully when you add all three to the larger flock.
Generally the recommended time to combine flocks is when they are about the same size, OR when the younger flock is 4 months old.
With two sets of chicks different sizes, the earlier you combine them, the better with the exception of when one group is day old. I'd give them a few weeks, in other words, if you are getting day old silkies and the other ones are three weeks old or bigger.
So, in summary, I would go ahead and get your silkies as many have them with their large fowl, with the caveat that you might need to separate them if the integration doesn't go well.
Additionally, silkies may require adjustments in terms of a nest box placed on the floor (covered kitty litter pans work well), lowered roosts or a pile of shavings on the floor for them to sleep on, and ramp slope adjustments.