I'm here to help share information about adding GST numbers in QuickBooks Online, @ajitparmar-gmail.
As of the moment, there isn't an integrated way to add more than one GST number or profile within one account. The idea is to make sure your taxes are calculated accurately that is why you're only allowed to a GST profile per account or subscription.
While the option is not yet available, let's consider letting our product developers know about your request instead. You can do so by sending feedback using the steps below:
Go to the Gear icon.
Select Feedback.
Enter a few words describing how you wanted to use more than 1 GST profile.
One QBO account is for one company file. You can manage branches/divisions by utilizing the Class/Location feature. Otherwise you should open a new account.