I'm not sure I understand what you mean but, you need a code for tool change even if you're working with gang tool in order to let the controller know what tool you are using but also the offset of the tool.
If you have 3 tools in the gang tooling holder, every time you switch between tool, you need to have a T2121 for first tool, T2222 for the second tool, T2323 for the third tool and so on.
Depend on how you number you tools.
If you wanf to have the tool stay close to the spindle for each tool change, just set the G30 where you want to have the tool change to be executed.
That's what I often do, also I remove the M5 (stop spindle)
Be carefull not to use a tool in the turret when the turret is near the spindle because you'll crash the turret on the spindle.
This is a video I made with gang tooling, you have to modify the program in order to remove every pauses between tool change.
Jeff