You can add multiple interfaces in one group. This page allows you to bind and unbind ports to a bridge group (bgroup) interface.
Physical Port: (Read-only) The physical ports located in the null security zone that can be bound to a bgroup interface.
Binding Bgroup: (Read-only) The available bgroup to which a physical port can be bound to.
Bind it to current bgroup: Select the checkbox to bind the physical interface to the current bgroup interface. Clear checkbox to place the physical interface in the null security zone.
After you have updated the ports to be bound or unbound to the bgroup, click Apply.