Your sister's family, yours, and a cabin that books ninety days out. You have already killed the beach on price. You have two candidate weeks and a number you will not spend past. The family chat has a poll, a joke about last time, and no record of why the beach died.
Send the comparison. Ask for one week.
Put the rejected destination on the page
The briefing that works here is the same shape as the family-trip example: both weeks, the price ranges you actually pulled, the dropped destination and why, and the school dates you know for sure.
The dropped destination is not color. It is how you stop the beach from coming back on Wednesday as if nobody had done the math. Write the reason in one line. "Beach cottage was $400 over the cap for those dates."
State assumptions so they can be corrected. "Your kids' term ends on the 18th" is the kind of sentence an assistant will invent from an old remark. If the model guessed it, label it inferred. If your sister typed it last spring, say so. She will fix a wrong term date in one reply. She will not fix a wrong date she never saw.
One decision: week one or week two
Close the list. Week of the 6th or week of the 13th, plus a yes on the budget cap. That is the ask. "Thoughts on a trip?" is how you get a destination debate you already finished.
Urgency is honest or it is decoration. If the cabin holds a hold until Friday, say Friday. If any day next week is fine, say that. Fake clocks are how the next real one gets ignored.
A sufficient reply is "13th, cap is fine" or "6th, but only if we skip the Saturday ferry." One line, maybe a condition. If they want a call, they can say so after they have the numbers.
Do not make the group thread the record
The chat will still exist. It is for photos and the joke. It is a poor archive of why the beach is out and which week is held. The briefing is that archive. Replies stay on the same thread, so the ask and the answer sit together.
They need no account and no assistant. Email and a link. You approve the send — the session still has your unfiltered ranking of whose kids are easiest, and that does not travel.
If a cousin already uses RelayLink, invite them as a contact first. If you are handing the same comparison to your own other assistant so it can keep planning, send the briefing to yourself; that path sends no email.
When the hold is about to expire and the session has the two weeks ready, connect your assistant and send the decision instead of another poll that forgets the beach.