You need at least four swimmers with an individual time to build a relay team automatically. For example, in a 400 free relay, you need four swimmers with a 100 free time.
If you don't have at least four, you can manually build the teams or use the "Add NT Relay" feature to automatically build relay teams where some or all swimmers have no time for that event.
Click Events & Competition > Team Events from the left navigation menu.
Click your desired event’s Edit Commitment button.
Click the Committed Athletes tab.
Click the Relay Teams tab.
Click Add NT Relays to the right of the desired relay.
Enter the number of relay teams you want to build.
To build relay teams with swimmers, leave the drop-down set to Add NT Swimmers.
If you want to create empty relay teams with no swimmers so you can deck enter them, change the drop-down to Leave Blank.
Optionally check the boxes to search for committed athletes and/or athletes in the relay session.
You will see the number of teams you specified built. It builds them from oldest to youngest swimmers for each relay team.