I like to think that all the siblings know each other. A lot of the canonical interactions can actually be read as familial with just small tweaks. Like, Sideswipe and Sunstreaker have a reputation of picking on the minis, 'cause they like to tease their younger siblings. And how often has Megatron been ready to land a killing blow on Optimus or another Bot, only to be distracted by Starscream in the nick of time?

And yeah, I remember reading that. Must be where I nicked the idea of Zephyrus.