Don't worry Scylla isn't left out of the cuddling, but Yin and Yang do cuddle with each other the most. Yang always likes to be snuggling with someone so Scylla and Yin usually oblige him. Yin actually likes to sleep alone so Yang is really the only cat she cuddles with.
Chimera also like to sleep alone and usually finds a hiding spot to sleep. So it's usually Yang cuddling with Scylla.
Although sometimes you will find all the cats in a kitty pile. ~ATCAD