Going on vacation with another family, and still being friends after

Everything is negotiable before the booking and almost nothing is after it. Sit down, or get on a call, with both sets of adults and agree four things.

Write the answers down somewhere both families can read them. It does not need to be formal; a short note at the top of the trip plan is enough. It is the thing you point back to on day four.

1. The budget, as a number. "Not too expensive" means different things to different households. Agree a rough figure per family for the accommodation and a sense of what a normal day out costs.
2. The style of trip. A list of three things each family would be disappointed to miss, and three things they would happily skip, shows the mismatch while it is still cheap to fix.
3. The pace. How many planned outings a day, and whether every day needs one. The family that likes a full schedule and the family that likes an empty one can share a trip, but not if each assumes the other is like them.
4. Who decides what. Each family books its own travel; one adult books the accommodation; anyone can propose an outing, but nothing that costs both families money is booked without a yes from each.

The fairest split depends on what is being paid for, so pick a rule per kind of cost rather than one rule for everything.

Per family suits things both households use roughly equally regardless of size: the rental, the cleaning fee, a shared car. Per person suits things that scale with mouths: groceries, restaurant meals, tickets. A family of five and a family of three splitting the food bill evenly is the classic quiet grievance. Per night suits a rental one family joins late or leaves early.

Then decide two smaller things. Whether children count as a full person, a half, or not at all for food. And whether the split is settled at the end of the trip or as you go. Settling once at the end, from a list everyone could see all along, is easier than settling every meal.

For a long weekend, a note on one phone listing who paid what, totted up on the last evening, is enough. The arithmetic gets harder with a week of shared groceries, two rules running at once and several people paying.

The friction on a shared vacation is mostly in the hours between the plans.

- Bedtimes and mornings. Agree what happens in the evening when one family's children go to bed and the other's do not, and who is quiet when in the morning. - Food. Allergies, the fussy eater, whether everyone eats together every night, and who cooks when. A rota for cooking and clearing up removes a surprising amount of tension. - Screens and rules. Two families' house rules will differ. The usual peace is that each family's rules apply to its own children, and both families agree on the handful that affect everyone, like the pool. - Time apart. Plan at least one day, or a few half-days, where each family does its own thing. It is not a sign the trip is failing; it is what keeps it from failing.

Trip Planner holds a trip as a destination, dates and a status: planning, confirmed, completed or cancelled. Inside it, the itinerary runs day by day. Each item has a type (transport, accommodation, activity, restaurant or other), an optional time and details, and room for a confirmation code and a booking link, so the code for the ferry is next to the ferry rather than in someone's inbox. Booking confirmations can be uploaded to the trip as documents, and the trip's notes field is a good home for the decisions from the first conversation.

The Details tab has a "Who's coming" list, which decides whose personal packing lists appear on the trip. Each trip that is not cancelled also appears on Calendar for its dates, so it sits alongside everything else the household has on.

Adults create and edit trips and itinerary items. At home, children can see the plan and keep their own packing list.

There are two ways to share the plan with the other family, depending on whether they use the hub.

If both families do, set up a shared Space for the trip. A Space is a separate shared hub with its own members and apps. Each family keeps its private household, and nothing crosses into the Space unless someone puts it there, so the other family sees the trip and its costs and never your calendar or your chores. Joining a Space someone else sponsors is free. Trip Planner and Expense Splitter both run in a Space, and any adult in it can add to the itinerary and log a cost.

If the other family does not use the hub, plan the trip at home and share it. An adult can create a read-only link to the trip: a page showing the destination, the dates, the status, and each itinerary item's day, time, type and details, plus a calendar link the other family can subscribe to. The trip's notes, booking links, confirmation codes, packing lists and documents stay in the household. Revoking the link stops it, including the calendar.

Packing is the other place two families double up. Each trip in Trip Planner has a shared list and a personal list for each traveller. The shared list is for the things one person brings for everyone: sunscreen, the first-aid kit, the board games, the beach shade. Agree who brings what before the day, so the rental does not end up with three kettles and no corkscrew. Whoever ticks an item off is named against it.

Adding to the shared list can also put the item on the household shopping list in Grocery, which is handy for the things that need buying first. Personal lists belong to their owner. At home any adult can see everyone's; in a shared Space only the Space's admin sees other travellers' personal lists, so nobody else is reading through yours.

Expense Splitter records each cost with who paid, a category, an optional receipt, and how it is split. Equal splits it evenly. Shares weights it, which is how to do per person or per night: give each family a number of shares equal to its headcount, or to its nights. Percent and Exact cover the rest, and a percentage saved for a category means Food can always split 60/40 while everything else splits evenly. Each person has a running balance.

Settling up records that a payment was made; no money moves in the app. If people save a payment handle on Venmo, PayPal, Cash App or Zelle, the person who owes can see where to send it. In a shared Space either side can also raise a reimbursement request, which both sides countersign before it counts.

Everyone in a split has to be a member of the household or the Space. For a trip with friends who do not use the hub, a dedicated splitting app, or the free expense splitter on our tools page, is the better choice.

Two families who agreed the budget and the pace before they booked, with a written note to point back to. One itinerary with the confirmation codes in it, one shared packing list with names against it, and a ledger both sides watched fill up, settled once at the end. Most of all, a trip both families would happily do again.

• Trip Planner
• Expense Splitter
• Calendar

Every app in the library is included with the household plan. Install the ones this guide uses and skip the rest.

• Expense splitting apps compared, by what each is for
• Sharing a lake house with your siblings without fighting over it
• Living with roommates: bills, chores, groceries and guests without the resentment