Hello @TAURUS The BULL - Thanks for reaching out.
I hope the above provided link helped solve your problem.
And If I understand your question correctly, Yes, you can have multiple sub users under One Single Azure subscription and with single billing credentials.
Your billing account for the Microsoft Customer Agreement contains one or more billing profiles that let you manage your invoices and payment methods. Each billing profile contains one or more invoice sections that let you organize costs on the billing profile's invoice.
Please take a look at this doc for more info : Billing Overview
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