How to message or invite a group without joining a group

Hello everyone,

I created a group(Job Post) with linked content types(Job details).

Scenario:
As a user, he created several jobs.

1. He want to be able to invite/message another group(Business) for them to be aware of his posting without joining this group.

2. Also, because he has more than one active jobs, he want to select a job to send the invite about.

3. Lastly, if he has already did an invitation to that group, he can no longer send twice.

Question:
How can I be able to achieve these three?

Thanks!

- John