I got used to have all my websites in /var/www so no matter which domain, each subdomain has its document root located in /var/www/
Plesk is trying to force me to use /var/www/vhosts/domain/ and I did not find a way to tell Plesk to just put everything into /var/www.
I don't want a whole new structure, I want to migrate my existing websites from my old server (without Plesk) to my new server running Plesk 17.8
Edit: Feel free to answer this question for future reference but I won't need it as I realized that no sane person would use Plesk. Server will be reinstalled.