Meeting invitations

I hope that someone can help with this. When inviting people to a meeting outside of the organisation (not in our team account), I schedule a meeting add the e-mail addresses and then send. If I then want to add someone else to this meeting, I've been adding the extra e-mail address and then clicking send again. This then sends all the candidates another link. Are both links valid for the initial participants and is there a better way of doing this so that the original participants don't receive multiple e-mails should I wish to add a few more people?

Thanks

Ben Hamilton