Saturday's game moved from Field 2 to Field 4 because of a tournament. You texted the other coach. They liked the message. Half your parents still have Field 2 in a calendar from March. At 9am you will have kids at two gates.
A field swap is a place and a clock. It is not a chat vibe. The other coach owes you a yes. Parents owe you an arrival. Those are two sends, in that order.
Hold the field first
"Can we take Field 4 Saturday 10am, same game, yes or no by Thursday 6pm. If I do not hear, I will keep Field 2 and tell the umpire." That is a decision for the other coach, or for the scheduler if that is who owns diamonds.
Write for a cold reader. They may coach three teams. Give the age group, the game number if you have one, the old field, the changed field, the start, and why it moved in a sentence. Cut the history of last week's argument about lights.
No schedule file. Write the one game. If the league site already has the grid, name the site.
Use names they recognise — team names parents use, not a private nickname for the other coach.
Then tell the parents who must arrive
After you have a yes, write to parents: same facts, one ask. "Field 4, Saturday 10am, drop-off 9:30 at the north gate, yes if you cannot make it so I can adjust the lineup, by Friday 6pm." A silent yes is allowed if you say so. A silent no is how you bat short.
They need no account. The mail is the product. They reply from the mail or the page. You approve every send. The league assistant does not move games as you.
If you use Claude and the other coach uses ChatGPT, you still agree in one briefing, not in two chats that disagree.
One parent per send when you need a counted answer. A team blast is how three people answer for a child who is not theirs.
What a sufficient reply is
From a coach: "Yes, Field 4." From a parent: "We cannot do 10 — sit this one out." One line.
Then a default. For the coach, keep the old field on silence. For parents, name whether silence means they are coming. Do not leave that implicit.
What this is not
It is not a protest about how the league assigns diamonds. It is not a conversation about playing time. A field is a field.
It is not medical advice. You can state a start time and a gate. You cannot tell a parent whether a child should play.
If your assistant already has the league note, let it draft the coach ask first. You read the fields. Then parents get the same facts once, after the hold exists.