Can we allow CLIENTS to late sign up for a class?

One of the websites I use Acuity Scheduling for is a dance studio, and we always have students arriving late, and I can't find a way to make their sign up process easy if they are a NEW client.

If they are an EXISTING student with a class pack, I can add them to the class using the scheduling app - no problem.

But if the are an EXISTING student wanting to pay for a drop in, I can take their payment in the app with cash, or use the Square dongle - no problem. If they want to purchase a class pack, that one's annoying because I need to ask them to use their phone to do it themselves in their web browser, I can't use the phone admin app to sell them a class pack - but that's a minor issue.

If they are a NEW client and arrive late, we still want them to be able to sign up online because that's how they fill out the class waiver. But there's not way to keep the class "up"/visible on the schedule after the start of class! We've tried adding a later "late sign up" instance of the class, but it clutters the schedule and confuses the students.

Surely we're not the only business that needs to handle late student sign ups! Any suggestions?

This is a HUGE issue for us.  Other scheduling software allows you to choose to keep signups open till end of class or 20 minutes after start, or whatever.

We can't seem to find an option that allows this on Acuity.

We offer 3 hour classes and people often come in 10, 15, or 20 minutes late... but once the class time starts, the registration closes automatically and nobody can sign up anymore. 

This is a HUGELY bad issue for our business.  Wish they would change this.

I came here thinking there must be some way to do this that I was missing. What a huge oversight - we have open sessions at our studio that last 6 hours, and people don't always decide the night before that they're swinging by. This means they end up having to pay with a Venmo QR code once they arrive, instead of through our website at all.

Seems like Squarespace wouldn't want to push businesses toward another company, for a product that they offer themselves? Squarespace, please change this feature to allow signups after the session has begun!