discount if I already have a Microsoft Defender for Endpoint license

Hi, I am looking to explore the Microsoft Defender for Endpoint server license vs Defender for servers plan 2 licensing.

We do have existing licenses available for Microsoft Defender for Endpoint server licenses and we would like to make use of this license in azure to avoid double payment of licenses.

Can someone help me understand how does this credit process work? i know starting point is raising a ticket with MS. Can we get the credit if we have only spare licenses? what if i have licenses being used on onboarded servers still can i request credit?

Also what is the easiest way to way to see how many Microsoft Defender for Endpoint servers license are in use right now?