Your hen will get off the nest for breaks, sometimes quite often if it's warm out. A half-hour or so to stretch the legs, poop, have a dust bath... Isn't going to harm the babies. Even longer is likely fine. But if she's not coming back to the nest or growl/purring, she may be losing her broodiness.
My SLW hasn't ever gone broody, but she's a big girl. I'd assume Silkie eggs should be okay, but I know some larger breeds can crush smaller eggs - like you could give a Silkie some quail eggs, but they prolly wouldn't last under a bramah etc...
Eggciting to hear they're developing well.
Our lockdown here was a bit bumpy at first but its getting much better now andi hope it gets better there to!Heard it's starting to toast up over there. We're across the ditch in NZ and it's a lovely spring day today... Now as long as everyone plays nice, we can get outta lockdown soon.