Add people to the roster, including players who never sign in, and bring in a sub for one night.
Your roster holds two kinds of player. Regular members are in the lineup of every new gig; subs are people you call when you need them.
Open the gig and change its lineup — swap the unavailable player out and the sub in. This affects only that gig. The sub does not become a regular member, and nobody else's lineup changes.
When you are picking a sub, RunABand suggests the ones who have not blocked out that date, so you are not offering a gig to someone who already said they are away.
Owners can add a sub by name and email from the Members page, without that person ever logging in. The membership exists immediately, so you can put them in a lineup straight away.
Claim links expire after 14 days. You can resend one at any time from the Members page.