Hello @rubberduckdev ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you would like to know if there is a way to add an Azure IP Group to an existing IP Group like a nested group.
As of today, an IP Group can have a single IP address, multiple IP addresses, one or more IP address ranges or addresses and ranges in combination. But not another IP Group.
Refer : https://learn.microsoft.com/en-us/azure/firewall/ip-groups
I checked with the Azure Firewall Product Group team and looks like Nested IP groups is currently not in the roadmap but is being considered for future improvement as we've received same feedback from other customers.
I'll raise an internal feedback item for this feature and route it to the Product Group team and would also request you to leave your feedback in the below forum requesting this feature. All the feedback you share in these forums will be monitored and reviewed by the Microsoft engineering teams responsible for building Azure.
https://feedback.azure.com/d365community/forum/8ae9bf04-8326-ec11-b6e6-000d3a4f0789
Kindly let us know if the above helps or you need further assistance on this issue.
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