The only way to sync one way, is to only make changes from one place... always work in FTM and sync or always work in the AMT and sync.
You are correct that uploading from FTM without linking does not allow for keeping the two trees current. It is not a solution if your goal is to have the same data in both places.
You are correct that uploading from FTM without linking does not allow for keeping the two trees current. It is not a solution if your goal is to have the same data in both places.