can't really tell by the pics but do they have 5 toes? The skin/beak coloring doesn't appear silkie so if they don't have 5 toes, chances are she is not the biological mom so you can probably rule her out. Other than waiting to see what they look like when they feather out, I'm not sure this is a mystery that you will solve unless someone admits to dropping them at your place when you weren't home.
