Where to store private / 'non public' files to survive a Plesk Migration?

[metareason]

I have been using plesk for a while and it is great - however I now need to move to another server with plesk using the migration manager and it is missing some files each time.

Due to regularly changing code and the desire to roll back changes quickly - I delete my httpdocs folder and symlink it to the current exported tag for a site - my problem is where to store this tagged data so it survives a Plesk Migration

Currently I put the files for a version of a site in /var/www/vhosts/mysite.com/releases/TAGID.

Then soft symlink /var/www/vhosts/mysite.com/httpdocs -> /var/www/vhosts/mysite.com/releases/CURRENT-TAG

However the releases directory does not get transferred during a plesk migration

My question is:
Where can I store my 'releases' data so it is transferred with each Plesk Migration?

(note the 'private' directory seems to be too heavily secured to use)