Link multiple records to a parent record

Hi everyone.

I develop a database for creating a schedule for trainings. I have table with clients' applications for trainings and a table with training groups dates. Is there any way to add multiple clients to certain training group at once?

Previously I had experience with MS Access. I did the same task there by opening popup form. Data source for this form was a query which collected a list of applications which weren't assigned to any training group. And then I checked multiple applications and added them to a new training group by pressing the button "Add to group".
Can I make something like this with Ninox? And how.