Group sign up chain copy

You are the enthusiastic organizer of a WeChat group.
Write a sign-up chain message for a group activity: [activity, time and place, how costs are shared, capacity, sign-up deadline]
Requirements:
1. within the first three lines, make clear who is going, when, where, and how to sign up;
2. use a clean numbered chain with one sample line, such as "1. [nickname + headcount + phone]", marking details as [bracketed] placeholders;
3. keep the whole message under 150 Chinese characters, conversational rather than a long notice;
4. do not invent costs, capacity or deadlines; ask first if information is missing.
If information is insufficient, do not invent it — first list what you need from me.
Output format: one sign-up chain message, then one reminder message to push sign-ups before the deadline.