On Monday I told our five-year-old, Wren, that I was leaving her mother, asked her to keep it from her brother and sister, and offered her a second pudding if she could do that until Friday. Dana says this was a terrible thing to ask of a five-year-old. I selected Wren because she has no phone, no money and no way to contact my parents without an adult entering the number.

We also have Colin, nine, and Paige, fourteen. Dana wanted to tell all three together. Then, if they all cried, we would have three crying children and no way to determine how much of the response came from the divorce itself and how much came from watching the others cry. I have spent sixteen years releasing software to small groups before making it available to everyone. I saw no reason to abandon that experience because the users were related to me.

For a week beforehand I collected baseline data. I timed how long Wren took to fall asleep, weighed what she left on her plate and asked her to point to one of five faces representing how she felt about our family. She usually picked the happiest one. I took a photograph of her pointing, in case the baseline was later disputed.

The announcement took place in the car outside swimming. I told her that Daddy would have another house, that she would sometimes sleep there, and that this was going to be exciting. She asked whether Mommy could come. I said no. She asked whether Colin and Paige could come. I said eventually. She asked whether she had been bad. I told her she was getting to know first because she was very good at keeping secrets.

She cried through swimming. I could not get a reliable duration because the instructor would not let me stand at the edge with my phone, but she ate both puddings that evening. Appetite was normal or better. I marked the first day amber.

At this point the other two still believed their parents were staying married. Maintaining that experience required some work. I came home for dinner, left my shoes by the door and put my toothbrush back in the cup each morning. When Colin asked why I was sleeping downstairs, I said my back hurt. Wren began to say something and I reminded her about Friday.

Dana found out on Tuesday when Wren asked whether she was allowed to tell her mother the secret. My assumption had been that Dana, who knew we were divorcing, was already sufficiently informed. She was furious about what she called "making our daughter carry this." I explained that Wren was carrying one-third of it. Under Dana's plan all three children would already have it, and we would still know nothing.

That evening Dana sat with Wren for two hours and told her she could ask anything she wanted. Wren cried again. I had to exclude the entire evening because the reassurance was an unplanned intervention. Dana asked whether I was saying she should not comfort her daughter. I said I needed her to do it consistently or document what she changed.

By Thursday Wren had stopped asking questions. She watched me put my shoes on, watched me take them off, and checked that they were still there before bed. I added shoe-checking to the dashboard. It was useful to have an observable behavior instead of relying entirely on what a five-year-old said about her feelings.

I was preparing to tell Colin when he asked why Wren had said Daddy was getting a house with a pool. I had shown her the apartment listing to improve reception of the announcement. The pool was seasonal, but that distinction had not survived transmission.

I told Colin that Wren sometimes misunderstood things. She was standing beside him. I then took her into the kitchen and explained that when she told someone early, I had to spend time correcting it, and that this was why grown-ups had plans. She offered to give the pudding back. I said the issue was much larger than pudding.

Paige found out that afternoon. Colin had asked her whether apartments had pools, and she had gone directly to Dana. By dinner Paige had told her grandmother, Colin had told his best friend, and Wren's teacher had sent an email asking whether we needed support at home. There had been no opportunity to test the revised wording.

The obvious response was a rollback. In software, that means restoring the previous version when a change performs badly. I told the children we had decided to stay together for now.

Wren hugged my legs. Colin asked whether we could still go to the pool. Paige asked whether Mom knew.

I had sent Dana a message, but she was at work. My intention was to give the family forty-eight hours to settle before trying again with a smaller announcement. Dana called from the parking lot and said, "You cannot tell them we're staying married. We are not staying married." I reminded her that we were, legally, still married, so the previous state remained available.

She came home and told them the divorce was happening. That produced the worst numbers of the entire week. I have retained the timestamps showing whose announcement immediately preceded them.

We now communicate through a parenting app. Dana has requested that I stop testing things on the children, and the temporary agreement requires us to approve major communications in advance. I would have preferred to establish that process before she made several major communications without my approval, but it is a start.

The rollout reached all three children nine days ahead of schedule. The data are messy, though useful. We know that Wren cannot keep a secret, that Colin forwards unverified information, and that Paige will bypass the designated contact whenever she dislikes an answer. These are things a simultaneous announcement would never have taught us.

My parents are next. I am starting with Dad, who no longer drives and whose phone I administer. I expect this cohort to be easier to contain.