They won't. The first chick my silkies hatched was a barred rock x wyandotte. They don't discriminate.They all went broody together (I have four). One was a week later, but pretty much at the same time. I thought it was strange, but this was their first time
being broody too. Their first time and mine. All the eggs at the same time, all silkie but the three AMs I put in. I didn't realize keeping them together was not a good idea. But why would they only attack the non-silkies?
Only issues with nesting in my experience is fighting over eggs. My girls traded back and forth. If one got up, the other stole the eggs and it continued. None were broken. However, when my cochin went broody, many tried to lay their eggs with her, and eggs were broken in the process.