Fancychooklady - I envy your ability to have enough of one breed that they can be a flock by themselves but in my backyard and zoned area, 5 is the maximum hens allowed and no roos so we had to carefully choose how to mix Silkies with LF. Like you I believe the breeds do navigate together and being in groups usually aren't bothered by other breed groups in the same area. However in our little backyard it is crucial not to have one huge LF among a couple 2-lb Silkies. Heavy LF like Orps, 'Lorps, etc though gentler tempered can still be tempted to bully smaller gentler bantams just because they can in a small yard situation - sadly experienced this when a 7-lb Marans viciously attacked a POL Silkie who screamed. The Marans also went after the alpha Leghorn. Needless to say she was instantly re-homed to an egg seller. No more breeds over 5-lb in the flock now and only docile types.
As for Silkies brooding other fowl - they will brood ANYTHING and hatch a snake egg if it was in their nestbox. My Partridge tried to brood a cucumber slice and another found a faux plastic egg to set so I don't think it's other breeds they respect so much as the opportunity to be a momma period. With their diminutive stature it probably makes the little buggers feel important to show off offspring of any kind - LOL!
I too have ' garden chickens ' and they are confined to a small area. I have a GLW living in harmony with my white silkie. Your situation was unfortunate , but not always the way it will be for others. I'm sure there are others that co habitate their breeds , my friend is in suburbia and it is her dream to have one of each.