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.