Changing personal plan + google account -> Business account

I currently have a personal account and pay separately through Squarespace for a Google email account. It is going to cost me pretty much the same if I go to a business account that includes a google email account. 

What I need to know is, if I cancel the separate payment for the Google account, will I have to start from scratch with a new account once I move to business plan? Or is there a way to just merge personal and google account during the upgrade process? Nervous about upgrading before I know what will happen to my existing google email account - ideally I want to maintain a consistently active google email account, with same email details.