limit number of submissions based on sum of a number input

It would be very useful, if another option is added to limit the number of submissions: So for example, assume you want to use a form for event registration and there is a maximum number of participants for this event, but with a single form submission it is allowed to register up to e.g. three people. So maybe you use a scale block, with that the user can set this number. Then it would be nice, if the form gets closed, as soon the sum of all submitted scale input values reached the maximum number of participants.