I got myself into a bit of bother earlier in the season trying to manage such a situation earlier in the season.
Poor tackle from green captain, should have been a YC, but no malice, he immediately apologised, checked fouled player, it was just a function of his (lack of) ability at this low level of the game. Fouled player was also happy (although hurt) that it was just “one of those things.” Temperature of the game was low, and green captain had been good as gold all game, pro-active and helpful. We had a “one way conversation” whilst player was being treated and I explained how close he had come to a card.
Green wall sets itself up ready for the free kick. Treatment finishes, “physio” (bloke with a bucket & sponge) leaves pitch, I don’t make injured player leave pitch.
I start to get verbals from one of the green wall - “he has to go off ref”. I, and captain, try to calm him down and shut him up, but to no avail. So I end up booking green captain, meaning injured player can stay on pitch, green captain accepts this graciously, other green players tell moaning green defender he should pay the fine. However, moaning green defender keeps chuntering on, so he ends up in the book, too, for dissent. Lesson learned- I should have just booked green captain in first instance.
Post script - 10 mins later, green defender who was whinging in the wall sidles up to me and apologises for being an ar$e.