Though you can make a Y cable that connects them, you will find that making it is difficult due to the wire / pin size. I would suggest using the 5 port hub or Y cable that Dynon sells.
I used their Y cable for the primary and backup AD-AHRS and the hub for joining everything else. Also keep in mind that most accessory items like the radio and intercom have two ports each and can be used to connect other items or daisy-chain the network.