I should probably have filled in the detail from the start, to avoid confusion.
Family camping trip; me+wife+2 kids + My (slightly older) sister+husband+2 kids.
Some sort of game was in play and my son (5) somehow kicked her daughter (10) on the leg (probably not entirely accidentally, but most likely through excitement, certainly not malice). There is no serious injury, not even a bruise or scratch, just a bit of upset.
I suggested that he apologise, but he was too embarrassed and shy (this is not unusual for him - he is highly sensitive and can be boisterous one moment and (literally)weeping and cringing with embarassment the next.) Situation develops into four other people simultaneously talking at him at the same time as me, trying to cajole him into apologising - this only drives him further into his shell and he bursts into tears. At some point along the way, I (perhaps foolishly) presented an ultimatum that he would miss out on a family meal if he wouldn’t say sorry.
In a flash of inspiration, my wife takes him to one side and asks him if he’d like to come and write a little note saying that he is sorry - he agrees, she helps him with the wording and spelling. The result is a very scrawly, tearstained, but still readable (and I do believe sincere) letter of apology.
I stay behind while he runs after the other family (who have now departed on foot toward the restaurant) to present the letter. Out of sight, but still well within earshot, I hear angry words and a sudden wail of despair, followed by the sound of my son returning in fits of tears. close behind him, my sister appears and tells me that the letter isn’t any good as it isn’t an apology from him because my wife ‘wrote it for him’ (various prognostications were also offered as to my son’s future character if we allowed him to get away with such things).
That’s about it - we very nearly packed up and went home there and then, but in the end we stayed the last night, exchanging only a few words as absolutely necessary.
It should be understood that the above is ‘my side’ of the story, however, I have made every effort to represent it as truthfully as I can.
So in this case, it is the mother of the offended party that is enforcing the rejection of apology.