unison start the sync from zero when I change the parent folder

I use unison to sync two folders that are in separate computers (via unison command with ssh). If for convenience I happen to change the name of the parent folder, unison start to sync the folders as if it were the first time I sync them, taking a lot of time (because the two folders are quite large). Here is the message I get: Looking for changes Warning: No archive files were found for these roots, whose canonical names are: /path/to/my/folder1 /path/to/my/folder2 This can happen either because this is the first time you have synchronized these roots, or because you have upgraded Unison to a new version with a different archive format. Update detection may take a while on this run if the replicas are large. Unison will assume that the 'last synchronized state' of both replicas was completely empty. This means that any files that are different will be reported as conflicts, and any files that exist only on one replica will be judged as new and propagated to the other replica. If the two replicas are identical, then no changes will be reported. Is there a way to tell unison that these folders have previously been synced? Perhaps changing the path somewhere and recovering the last unison file? Similarly, maybe a related question: if I copy one of my folders to a new computer and therefore they are already in that moment identical, could I tell unison that they are identical to skip the update detection process?