Good evening, @Chunn. I hope you're having a fantastic Friday so far.

To answer your question, yes, you can change the sign-in credentials so that both of your companies are under the same User ID/email. Here's a Community Article that walks you through the process by providing detailed steps: Sign in to multiple QuickBooks Online companies with one user ID.

If you hit any bumps, please don't hesitate and reach back out to me. I'd be happy to help you out. Have a great weekend!