terminal – Granularity of tmutil’s associatedisk function

I want to look at options for moving a home directory off a boot drive, and onto a different physical volume.

What I need to avoid, is time machine treating it as new data, and doing a full backup, because that will cause older backups to be deleted, as the TM disk will run out of space, making double copies of files that haven’t been changed in years, and deleting the older versions (which I want to preserve) of those that have. Everything in this case is HFS+, and this system is not migrating to APFS, for (reasons).

I know you can use associatedisk if for example you’ve copied the data on a drive to a new physical drive, and you want its backup to be a continuation of the old:

sudo tmutil associatedisk -a /Volumes/TheNewDrive /Volumes/TheBackupVolume/Backups.backupdb/ComputerName/YYYY-MM-DD-TTTTTT(newest backup)/TheOldDrive

But can you also target individual folders wihin the backup, something like:

sudo tmutil associatedisk -a /Volumes/TheNewDrive/UserHomeDirectory /Volumes/TheBackupVolume/Backups.backupdb/ComputerName/YYYY-MM-DD-TTTTTT(newest backup)/TheOldDrive/Users/UserHomeDirectory

Or, is associatedisk limited to only connecting the root level of drives to backups?

Thanks.