Your co-parent joins free, on every plan. One subscription covers the whole family, so whichever of you pays, the other never sees a bill.
- Open Invite in the app, or Settings → Co-parent.
- Send the link by email from inside the app, or copy it and send it yourself.
- They open the link, create an account and confirm their email.
Until they accept, messaging and calls are waiting on them — everything else you set up now (children, schedule, expenses) is there when they arrive.
If they already have an account
That happens when they signed up on their own before you invited them. Opening your invite link explains what joining involves and offers to close their empty family first. See Joining when you already have an account.
An invite link is for one person. Don't post it anywhere public — anyone holding it can join your family.