Hi Aleksei Petrenko,
Transferring Azure credits from your co-founder’s account to your own is possible, but it is not a self-service process. To initiate this, please submit a support ticket to the Startup Support team, clearly indicating that the request is related to an "entitlement transfer."
Please refer to the doc, Azure Credits and Billing FAQs
We recommend reaching out to Microsoft support for further assistance Submit Support Request.
Please reach out to us if you have any other queries.
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