Enabling WRSM in Windows Server 2012 R2 to manage resouses used by each user:
https://www.vioreliftode.com/index.php/windows-system-resource-manager-and-windows-server-2012-r2/
Enabling multiconnection in windows 7, 8.1, 10:
https://github.com/stascorp/rdpwrap
https://winitpro.ru/index.php/2015/09/02/neskolko-rdp-sessij-v-windows-10/