Secret Santa generator with exclusions for couples and housemates

Your group has a married couple in it. Maybe two sisters who share a kitchen, or two people whose desks touch and who already buy each other something every December. Pull the names out of a bowl and there is a fair chance one of those pairs comes up matched, and then two of the gifts in the room are household purchases wearing wrapping paper.

An exclusion is the fix. You name two people, the draw refuses to pair them in either direction, and nobody has to redraw in front of an audience. Bringalong asks for exclusion pairs on the screen after the names, then hands you one private link per person, so the pairing stays out of sight, including yours.

What organizers get wrong is quantity. Exclusions are easy to add and they compound. One blocked pair in a group of six still leaves 168 possible draws, which is plenty. Block a whole department from itself and there may be no valid draw at all. This page is about where that line sits and what to do when you hit it.

What an exclusion is, and what it cannot do

An exclusion is a pair of names held as a rule rather than a preference. Mark Beth and Sam and the draw will not give Beth to Sam, and will not give Sam to Beth. It works in both directions on purpose. A one-way block is rarely what anybody means: if Beth should not be buying for Sam, the reason usually runs back the other way too.

It is not a wishlist of people you would rather have, and it is not a ranking. There is no way to tell the draw that Omar should ideally get Clara. Every allowed pairing stays equally likely, which is the part that makes it a draw at all. Exclusions take options away. They do not steer the result toward anything.

The requests worth honoring are the ones you could describe to the whole group without embarrassing anyone.

• A couple, or two people who live in the same house.
• Siblings young enough that one parent would end up buying both gifts.
• Two people who already swap a gift privately, so the draw would duplicate it.
• A pair who drew each other last year and would like a different name.
• Two people whose falling out is already known to the group.
• A manager and the person they line-manage, if a gift from one to the other would read oddly.

Why a couple drawing each other spoils the point

Say Beth draws Sam. They share a bank account and a car. Beth buys the gift with money Sam watches leave the account, wraps it at the kitchen table he walks past twice an hour, and hides it in a flat they both clean. On the day, Sam opens a present from the one person who was going to give him a present anyway.

A draw exists to move a gift along a line nobody expected. A six-person exchange has six of those lines. When a couple takes one of them, five people get a surprise instead of six, and the couple have spent their money on each other, which was already happening. The same logic covers parents and small children in a family draw: the gift gets bought with the same card on the same shopping trip.

There is a secrecy cost as well. Beth has to keep a name from the person she shares a hallway with for three weeks, and Sam has to notice one parcel. Couples are poor at keeping secrets from each other for reasons that have nothing to do with carelessness.

A worked draw: six names, one blocked pair

Nadia, Omar, Beth, Sam, Clara and Luis are taking part. Beth and Sam are married, so they go in as one exclusion pair. Here is a result the draw could return.

Everybody gives once and receives once. Nobody is holding their own name. Beth has Luis and Sam has Clara, so the married pair are pointed away from each other and neither of them can work out their own giver from what they can see.

Now count the alternatives, because that is how you see what the exclusion cost. Six names with nobody holding their own name has 265 possible arrangements. Blocking one pair in both directions knocks out 97 of them and leaves 168. The draw still has room to surprise people, which is the whole reason to run one.

• Nadia gives to Sam
• Sam gives to Clara
• Clara gives to Beth
• Beth gives to Luis
• Luis gives to Omar
• Omar gives to Nadia

What the second and third exclusion cost you

Keep the same six names and add a second couple, Clara and Luis. The 168 arrangements become 116. Add a third pair, Nadia and Omar, and you are down to 80 out of the original 265. Three exclusions in a group of six have taken about seven draws in every ten off the table, and the result starts to feel predictable to the people in it.

That still works. It stops working when the group is small. Four names with one blocked pair leaves four possible arrangements, and adding a second blocked pair leaves the same four, because the first exclusion had already removed everything the second one would have removed. Four people in two couples is not a draw. It is a rota with a couple of settings. Three names with any exclusion has no answer at all, so a draw of three has to run clean.

Larger groups absorb exclusions without complaint. Eight names with four couples in them has 4,752 valid arrangements, down from 14,833. Nobody in that room will sense the difference.

• Six names, no exclusions: 265 arrangements.
• Six names, one blocked pair: 168.
• Six names, two blocked pairs: 116.
• Six names, three blocked pairs: 80.
• Four names, one blocked pair: 4.
• Three names, one blocked pair: none at all.

When no valid draw exists, and how to get one

Pile on enough exclusions and there is nothing left for the draw to return. It usually takes one of two shapes: a small group where most people are paired off, or one person who has been blocked from so many others that nobody is left to give to them.

Work through the fixes in this order, because the early ones cost nothing and the last one costs a participant.

1. Count the names first. Under six people, carry one exclusion pair at most.
2. Delete the exclusions with no reason behind them, starting with desk neighbors and last year's repeats.
3. Add people. Going from six names to eight lifts the number of possible arrangements from 265 into the thousands.
4. Split the group. Two draws of eight work better than one draw of sixteen with a whole team sealed off inside it.
5. Replace a team-wide block with the two or three pairs inside that team who have an actual reason.
6. As a last resort, take one excluded pair out of the draw and let them give each other their gifts directly.

Why blocking a whole team from itself usually fails

This is the request that breaks draws. Eight people in the exchange, five of them in marketing, and somebody asks that nobody in marketing draws a teammate because they see each other all day. It sounds reasonable in a meeting. It is arithmetically impossible.

Each of the five has to give to one of the three people outside the team, and each of those three can only receive one gift. Five givers, three slots. The draw will not find an answer however long it runs, because there is no answer to find, and no software can rescue that.

The limit is half. A block of people all excluded from each other cannot be bigger than half the group. Four sealed-off people inside a group of eight does run, with 576 arrangements available, but look at what the result hands them: each of those four knows their own giver is one of the four people outside the team, and each outsider knows their giver sits in marketing. Sealing off a team swaps one mild annoyance for a much shorter guessing list. Mark the two or three pairs with a real reason and let the rest of the team draw each other.

Explaining the rule without naming who asked for it

Somebody will ask you to block a pairing for a reason they would rather not share. Treat the request as confidential by default and announce the rule as a property of the draw rather than a favor to a person.

Say it before you run the draw, not after, and say it once in the group chat where everyone reads the same sentence. One line covers it: the draw blocks a few pairs, mostly people who live together, and if you think you belong on that list, message me by Thursday. That sentence hides the pair who need hiding behind the couple everyone can already guess, and nobody has to explain themselves in front of twelve colleagues.

Then hold two things. Do not confirm or deny an individual block afterward, even to the person who asked, because an answer given to one person is an answer given to the group inside a day. And do not read the exclusion list out when you run the draw. Nadia does not need to hear that she was blocked from Omar, and if she works it out later, she worked it out on her own.

• Collect exclusion requests by direct message, not in the group thread.
• Tell the group that some pairs are blocked, without saying which.
• Give one deadline for requests, then close the list and run the draw.
• Do not pass a request on to the other half of the pair.
• If a request arrives with a story attached, keep the story.
• Turn down anything that is a preference for a particular name rather than a block.

Running it here

Names go in first, exclusions on the next screen, then the draw. You set the spending limit and the exchange date at the same time, and both appear on every private link, so nobody has to scroll back through three weeks of chat to remember what was agreed.

The draw itself runs on the server. You get a list of names with a link beside each one: you can copy a link, you cannot see where it points. If you are in the draw yourself, your link behaves like everybody else's. Nobody is assigned their own name and no two people are assigned to each other, so exclusions on top of that are for the pairs who share money or a roof, not for the mechanics.

Keep a note of which name maps to which link until the gifts are handed over. Bringalong does not send mail, so a lost link has to come back from you, and rerunning the draw changes every match in the group, including the ones people have already shopped for.