Adding switch to fabric

All,

We have a Hp enclosure and it has 2 small brocade switches on them. Our previous team ran physical cables from both the switches to both our production fabrics. But they did not use a unique domain id, so they are not connected to any fabric.

Now i intend to change the domain id, once i change the id to unique number, will it connect to both the fabrics? If so, what problems do you think i will face?

If the switch is connected to both the fabrics, will it combine zones from both fabrics ? Is there a chance i might face issues such as all the zones on both fabrics overlapping and gets crashed ?