F5 Active Stand by Sync config - order

When you're on the sync page there's options to sync from either device to group. Sync from the device that has changes on it to the group. Its different between versions but it is a little confusing the way the page is written.

On a good note, you haven't changed anything to the config of the traffic device, so you could also just make the changes on that device and overwrite your standby device. Typically I recommend making changes on the active and syncing to standby.

Also, you mention adding routes. If those are TMM routes on the device, you'll want to add that separately as it won't get synced. If you sync without adding a static route on the other device, those pool members won't be accessible.