Creating a SQL Server Distributed Availability Group across two Availability Groups on the same instances

I have a scenario where I want to create a SQL Server Distributed Availability Group (DAG) that spans across two existing Availability Groups (AGs) residing on the same set of SQL Server instances. Here's the setup: - I have an Availability Group named "ag1" with two replicas: "instance1" and "instance2". - I also have another Availability Group named "ag2" with the same two replicas: "instance1" and "instance2". My goal is to create a Distributed Availability Group named "distag1" that encompasses both "ag1" and "ag2". I followed the documentation and attempted to create "distag1" on the global primary (the primary replica of "ag1"). It was created successfully. However, when I tried to join on the other end of "distag1" (the instance that ag2's listener points to), I encountered the following error: ALTER AVAILABILITY GROUP distag1 JOIN AVAILABILITY GROUP ON N'ag1' WITH ( LISTENER_URL = N'TCP://ag1lsnr:5022', FAILOVER_MODE = MANUAL, AVAILABILITY_MODE = ASYNCHRONOUS_COMMIT, SEEDING_MODE = MANUAL ), N'ag2' WITH ( LISTENER_URL = N'TCP://ag2lsnr:5022', FAILOVER_MODE = MANUAL, AVAILABILITY_MODE = ASYNCHRONOUS_COMMIT, SEEDING_MODE = MANUAL ); Msg 19509, Level 16, State 0, Line 38 Cannot create a distributed availability group 'distag1'. An availability group with the same name already exists. My question is: * Is it supported to create a Distributed Availability Group across two Availability Groups that reside on the same set of SQL Server instances? * If it is supported, what could be causing the error message I encountered? Are there any specific requirements or considerations I need to take into account when creating a DAG in this scenario? I would greatly appreciate any insights, clarifications, or guidance on this matter. Thank you in advance for your help!