How to transfer Microsoft Startup credits from a private account to a business account?

I have the following situation: I applied for MS Startup credits and used my Gmail managed email to create a new MS account. This is a private account. The MS Startup Credits were assigned to that account and I started developing my app.

I am now interested in building a production-like setup in Azure and would prefer to do this in a business account. I created a new account, moved my GMAIL email to that New MS business account (closed my google account) and now ended up with two MS Account logins, using the same identical email (as login): one for private, one for business.

I change the email for the private account - as that was just way too confusing.

I like to build the production-like environment using the Startup credits. I now have three options:

1. Build it in the private account using the credits (that's where the credits are)
2. Build it in the business account and pay for the services
3. Build it in the business account but somehow access the startup credits

Option 3 is my preferred option but support (Billing & Subscription) wasn't able tp help.

Is there a way where I can either access the credits assigned to another account OR
Can I transfer the credits from a private account to a business account?

Cheers
Axel