Open invite to a team rather than individual assignment

Does anyone know if you can send an open invite to fill a position for a service with Planning? I.e. I've an extra prayer meeting on Saturday that's not part of our regular service schedule so I'd like to be able to ping an email out to the tech team and see if anyone signs up to cover rather than assigning a number of people and hoping that they accept.

WorshipTools doesn't have the option to send open invites at this time. Instead, these are the current options for inviting people to services:

1. Assign roles and send invites – Add the roles you need in the People tab, assign individuals, and send invites for them to accept or decline.
2. Scheduling Matrix – Use the Scheduling Matrix to quickly see availability across services and assign people accordingly.
3. Workaround for open invite – Create the service with empty roles, email your team with the plan link, and assign people once they reply.

That would be a great feature!
I currently have a group in messages for each team and message the team in situations like this, then add the correct people into the service afterwards.