A conference sells tickets. The same weekend, a church takes an offering and a school sells reunion shirts at the door. If each of those lives in a different tool, the report is a reconciliation project.
One event, one set of numbers
Ticket sales, gifts against a campaign goal, and merch sold online or at the door should sit next to who actually arrived. The person who asks for the report should not have to add them up.
That is the shape of a Parmlog event: registration and tickets, a donation page, a merch shop, and the check-in list, written into the same record.