Question
Is it possible to specify a custom path to document root for additional domain or subdomain in Plesk?
Answer
Yes. Document root directory can be specified:
Note: It is not possible to specify an empty path or put just /
there for security reasons. The corresponding record is shown on such attempts.
For new additional domain or subdomain
In Plesk > Subscriptions > example.com > Add Subdomain specify the required path in the Document root field
For already existing additional domain or subdomain
In Plesk > Subscriptions > example.com > new.example.com select Hosting Settings and set new path in Document root field
Note: Existing files will be copied over to the new document root. Both document root directories will exist: