With supervision - what cause the booboo? The reason I am asking is often times polish birds do not mix well with full size birds. But the size thing is not so different at 6 weeks as it will be later on, so might not be a problem at this time.
I would watch, I would not expect a lot of trouble at this young of age...but how did she get hurt before?
How much space do you have? Are they in the coop? Space can cause problems as they grow.
I would watch and carefully monitor. But I don't think you will have a problem unless you had a problem that caused this, then it will get worse.
Mrs K