Sure - just make it INVITE ONLY (under Advanced Options on Tournament Create).
Then use Invite Players (under TD Tools); Invite a group I manage.
The final setup screen looks like this ...
Invite individual players
* Invite a group I manage
You are allowed to invite up to three times the number of max players minus players already registered (see formula below). As your invites are accepted/declined, you are allowed to invite more players.
(3 * ) -
Usernames:
Enter in up to 15 usernames comma separated.
Enter in up to 15 usernames comma separated.
Message:
Is it possible to have an intra-group tournament i.e. within members of the same Group?