Yes wanting to keep up it exactly correct! And it has made them more advanced than their mamas were at their age (when I first brought chickens... they were supposed to be my only chickens - what's this chicken math anyways? is is contagious?). Keeping up with the regular sized chick and the other chickens has made them already flap/hopping up onto the roosts (No! don't go there!), running everywhere after the others (what?! where?! how did you get there - sheesh!), they love Mount Poopmore (manure pile), and they have learnt that the horses paddocks are great place to run and hide - brats!Plotting stealing more treats over a shared meal. poor girlies just wanted to keep up.
If I had Silkie chicks again I would definitely mix them in with regular chicks, and my three are the boss over their brother is twice their size!