Silkies are a VERY broody breed. And it's not uncommon for them to go broody 3+ times a year.
So if you are against broody chickens they probably aren't the best choice.
Buff Orpington’s are a great breed and are very calm and docile. Silkies and Cochins are also very calm and docile just like the Buff Orpingtons.
Docile breeds often get along extremely well so these breeds should mix together with no issues.