You cannot managed the Brocade, because most probable those Switch are not Seed Switch in the Fabric, and /or the zoning config is set in defaultzoning disable or mcdata mode.
since this is a small fabric,
1) I would proceed with another method and suggest, to create a NEW Config in the NEW 300B you want to add, and handle this new 300 as a second Fabric
2) Leave NEW 300 in Native Mode, assign a unique Domain ID, and move one path,
( i think you have multipath storage and connectivity ???? ) from current Brocade/McData Fabric to NEW 300.
After you have move the path make sure the NEW fabric is work.
At this point, disconnect the McDATA from a Fabric.
At next step, I would turn back the both Brocade 300B from Interop-Mode to Native Mode.
Keep in mind, this operations is disruptiove, however if your NEW Fabric creation as suggested by 1) and 2) was successfully configured and the Traffic is work fine, you should not have anything of impact.
After the both Brocade was set in Native Mode, make sure both have unique Domain ID, and add in the NEW Fabric.
so basically you think i can actually attached a brocade to this fabric in native mode and it will merge and obtain the zoning information? That is much easier to recreating it obviously and quicker.
I am aware that changing the interop mode will basically reset the switch but i do want them all in native mode. Thanks a lot for the response I'll let you know how it works.
--->>>so basically you think i can actually attached a brocade to this fabric in native mode....
you cannot ISL this NEW Brocade 300 in native mode to a Interop-Mode fabric.
instead, you should create on this NEW Brocade a new config as separate Fabric and move all the connectivity from one of both 300 in IM Fabric to new Brocade.
put the Old Brocade in Native Mode ISL to new Fabric, and continue to move the other connectivity.
and so on.
at the end you have moved all connectivity from, and can dismiss the McDATA.