Help Needed: Setting Up a Distributed Availability Group with Manual Seeding in SQL Server

Hello SQL Server Experts, I'm in the process of configuring a Distributed Availability Group (DAG) in SQL Server and am looking for guidance on implementing it with manual seeding (back up restore) instead of the automatic seeding. The DAG I plan to set up involves two normal Availability Groups (AGs) named ag1 and ag2, each serving as a replica within the DAG. My aim is to replicate the following topology:

+--------------------+         +------------------------+
|  WSFC1             |         |   WSFC2                |
|  +--------------+  |         |  +------------------+  |
|  | AG1 (P)      |  |         |  |  AG2 (S)         |  |
|  | +---------+  |  |         |  |  +-------------+ |  |
|  | |node1 (P)|  |======DAG=====>|  |node3 (P)(F) | |  |
|  | +----+----+  |  |         |  |  +-----+-------+ |  |
|  |      |       |  |         |  |        |         |  |
|  | +----v----+  |  |         |  |  +-----v-------+ |  |
|  | |node2 (S)|  |  |         |  |  |node4 (S)    | |  |
|  | +---------+  |  |         |  |  +-------------+ |  |
|  +--------------+  |         |  +------------------+  |
+--------------------+         +------------------------+
In this topology, we have:
- 4 nodes: node1, node2, node3, node4
- 2 WSFC clusters: WSFC1 and WSFC2
- 2 AGs: AG1 and AG2
- 1 DAG, from AG1 to AG2
- (P) = primary replica
- (S) = secondary replica
- (F) = forwarder

The official Microsoft documentation (Configure Distributed Availability Groups) primarily covers the setup using automatic seeding. However, I want to utilize the traditional backup and restore method. Unfortunately, I am uncertain about the correct sequence of operations regarding when and where to take backups and where to restore them within this topology. Could anyone provide a step-by-step guide or clarify the process in plain English on how to create a DAG using manual seeding? Below is what I have pieced together so far, but I'm stuck on the ordering and appropriate steps: * Enable the Always On Availability Groups feature on all instances. * Create an endpoint on all instances. * If ag1 and ag2 span across different domains, configure the endpoints to authenticate via certificate. * Take a full and log backup on node1, then restore them to node2, node3, and node4 using the NORECOVERY option??? * Create ag1 on node1. * Create ag2 on node3??? * On node1, create the DAG that includes ag1 and ag2. I'd greatly appreciate any help or resources that could point me in the right direction. Thank you for your time and assistance!