Make an arrival sheet for each party
Give all travelers the address, recognizable entrance, arrival window and the official way to contact the host. Identify the first adult who can complete check-in. Some properties require the booker or another named guest, so a key box alone does not establish that every traveler can arrive independently.
Plan for an early or late arrival
If one group reaches town at noon but check-in starts at four, ask whether luggage can be left or choose an independent place to wait. If another group will arrive after the host is available, agree on a supported access arrangement. Do not give out a private code to someone who has not been authorized to use it.
Keep changes in one current message
Share the address and practical directions with everyone who needs them. Send door codes only to the travelers who need access, through a suitable private channel. If the host changes access instructions, replace the old directions so nobody waits at the wrong door.
If the host says to use the courtyard door instead of the main entrance, send a single corrected instruction to the travelers who need it. Retire the earlier note rather than leaving two plausible routes. Confirm the first guest got in before sending everyone to a door that may only work during staffed hours.