Looking for ideas here...

OK, customer runs a manufacturing business. A local web developer solicits them, convinces them to let him move their website onto his system.

He then promptly disappears. No phone calls, no e-mail, no anything for 3 months by the time they called me looking to fix things.

Since we have no access to FTP or anything except the OpenCart admin, we agree to a basic rebuild of the website and a redeployment onto a SiteGround account that they control. Dev process goes smoothly, customer is happy.

Come time to launch and...naturally, the previous dev pointed the nameservers to his account, which will not allow the business to make changes because they aren't the account owner.

"We can work around this," I figure, since all we *really* need to do is change the A records, and we can leave the e-mail set up as it is (hopefully).

Well, that hopefully is kind of true—turns out instead of being set up in GoDaddy (where the domain is registered) it's set up in Gmail—and the customer doesn't know which account is the Google admin account associated with the domain. For all we know it could be the previous developer—again.

I've been able to dig up the A, MX, and TXT records, and I'm seeing references to dreamhost.com (where the nameservers are at) in the SPF data in the TXT records. Am I going to have to update these records, or will it be safe to just leave them as they are and simply update the A record as originally planned?