Adult only. Private by design.
What adding a round does

The button adds one planned round. It does not pair anyone yet.
The short answer
Add a round is a button on a key party. Your host invites friends. The host invites friends they'd love to have there. One private link per couple. It raises the planned count by one. If no count is set yet, the plan becomes one more than the rounds already revealed.
The line above the button says there are not enough mutual matches for another round, or it says how many more rounds those matches cover. The button stays off when the matches do not cover another round without repeating a pair. It also stays off at 12 rounds. A party can have at most 12 rounds.
Adult only. Private by design. You confirm you are 18 or older. The host still checks you in. A private no stays private.
Taking a round off
Remove round, with the current number, shows only when that round has not been revealed. The note says revealed rounds stay, and the party keeps at least 1 round. Pressing it lowers the planned count by one.
A couples only key party does not show Add a round. Couples only pairs each couple once. A play party does not show the button. A speed date does not show it either.
Once the night is revealed, or set to no reveal, the card is gone. If the night is already over, the action is refused.
What Add a round is not
This is not Start another round. That button comes after a reveal. It pairs checked-in guests from yeses they already gave. Add a round only changes how many rounds are planned, and it does that before the reveal.
It is not Allow a repeat match, and it is not Re-roll. Re-roll picks a different full pairing before the reveal. Add a round does not pick a pair, open the cards, or check anyone in.
A co-host can press it from the dashboard. They still cannot delete the party or remove the original host. A night in Chicago can use the button. Dallas can too. Those cities have their own pages. The count still lives on the party.
A planned round is not a reveal
All mutual-yes matches are revealed by the format the host already chose. Adding a round does not reveal them. A one-sided yes stays hidden.
A key party shows one Play Partner at the same time, after the host starts the reveal. A play party keeps matches hidden until the host reveals them. A speed date is short rounds, then yes or no.
FAQ
Why is Add a round off?
Mutual matches do not cover another round without repeating a pair, or the party is already at 12 rounds. A party can have at most 12 rounds.
Can a revealed round come off?
No. Revealed rounds stay, and the party keeps at least 1 round. Only a round that has not been revealed can come off.
Is this Start another round?
No. Start another round is the button after a reveal. Add a round changes the planned count before that, and it does not pair anyone.
Does a play party use it?
No. Play parties do not use pairings or rounds. A speed date does not show the button. Couples only pairs each couple once.
When do matches show?
All mutual-yes matches are revealed by the format. A key party shows one Play Partner at the same time, after the host starts the reveal. A play party keeps matches hidden until the host reveals them. A speed date is short rounds, then yes or no.