Hi Tman,
Generally speaking, no, gigaACE is not designed to be networked through a switch. It is a point-to-point connection so each of your cards can only talk to 1 other device. (The B port on each gigaACE card is for redundancy purposes only, so the card should never be used to connect to two separate devices).
To connect three systems together over gigaACE, you would need 4 cards. 2 to link System A and System B, 2 other cards to link System B and System C. You can then use tieline patching on System B to send audio from A to C or viceversa.
Other protocols such as Dante are generally better suited for networking more than 2 systems together, and more easily supported through network switches.