People who have accepted (an invitation)

I am sending invitations to people who are eligible to become members. I am wondering what other word I can use that means something similar to 'member'.

Specifically, I have invited certain people ('invitees'), and some of them have accepted my invitation.

I'm looking for a word like 'accepteds' (which I know is not the right word to use), because they accepted my invitation and so their status has changed from invitee to XXXX (a noun based on or associated with a verb that means 'to accept').

I know this sounds like a silly question, but in my own language you can name such people by reference to their action.

Thanks in advance. :)

According to Wiktionary acceptee is a real word, though I have to say I have never heard it actually used.

acceptee (plural acceptees)
A person who accepts, or is accepted for, a position