Distributed Availability Group with Manual Seeding

I am looking for a step by step walk through of how to setup a distributed availability group with manual seeding. I can get the automatic seeding working but when I try to manually seed I cannot get the secondary database into the AG on the forwarder. If I add the distributed AG to the secondary before I try to add the database to the regular AG I get the following message: Msg 41190, Level 16, State 7, Line 22 Availability group 'MYDB' failed to process add-database command. The local availability replica is not in a state that could process the command. Verify that the availability group is online and that the local availability replica is the primary replica, then retry the command. If I try to add the DB first without joining the Distributed AG on the secondary, I get the following message because it thinks it should be a primary: Msg 927, Level 14, State 2, Line 22 Database 'MYDB' cannot be opened. It is in the middle of a restore. I have none of these problems with automatic seeding. Everything just magically works. All of the examples I find online use automatic seeding. thanks in advance