Hey James,
Thanks for reaching out to us!
Unfortunately this isn’t currently an option with our ticketing plugins. However, there are some big updates coming to the way that we handle our ticketing solutions. With this will come a new “Tickets Meta” option that will allow for additional information such as this to be added to individual tickets when purchased. If you subscribe to our newsletter (form found in the footer of https://theeventscalendar.com/), you’ll be notified when this update will be ready.
If this doesn’t work for your project’s current timeframe I definitely understand. As an alternative, you could look into doing a little customization on your current Ninja forms approach. You could add a “quantity” field to the form for the number of tickets for each submission. You could then track this total number and then disable the form when the accumulation of that quantity for all entries has reach the number of tickets available.
Let me know if this helps.
Thanks!