The documentation has diagrams with availability groups taking part in multiple Distributed Availability Groups (AG 1, AG 2 and AG 3) take part in Distibuted AG1 ([AG 1, AG 2]) and Distributed AG2 ([AG 2, AG 3]).
Is there a limit to this?
The documentation says "As long as two availability groups can communicate, you can configure a distributed availability group with them".
The documentation also says "In other words, a primary replica can participate in two different distributed availability groups"
Is 'two' the max? Or just used for the purpose of illustrating that there can be more than one. Can a primary replica participate in three different DAGs?
The book "Pro SQL Server Always On Availability Groups" says that an availability group can be a member of more than one distributed availability group, it does not explicitly say two. https://link.springer.com/book/10.1007%2F978-1-4842-2071-9