Some polish can be kept with other breeds but there is always the risk of them being picked on by the other flock members. 9/10 polish are at the bottom the pecking order.
Is your polish broody now? They are not really a broody breed so it's great if she is. Out of all the polish I have and have had only one has ever gone broody. If she is broody I would highly recommend you seperate her from the flock to hatch and raise chicks.
I'm afraid more than likely it will be picked on by other flock members. Silkies are often at the bottom of the pecking order in mixed flocks. I can't say this will or will not happen but there is a chance.