With a single click team members can reserve a "seat or position" to attend the training! They can only reserve their own place and only one time. One can see a list of all the other attendees and positions for a specific training and/or team. There is a special "admin" view where an admin can add or remove all team members from a drop down list (regular can't do that, they can only add their own name).
I've search for this solution a long time and with the outstanding help of the head developer of Jevents, it was all done within 3 days! I am still amazed by that..