A lead becomes a booking, a booking is attended or is not, and an attended booking becomes a customer. Those changes happen days or weeks after the click, usually in a CRM rather than on the site.
POST /leadsandPATCH /leads/{uuid}, withleads.write.POST /bookingsandPATCH /bookings/{uuid}, withbookings.write.
Update rather than recreate
A booking that is attended is the same booking, patched. Posting a second one counts two, and the funnel then reports more bookings than leads, which is the shape the product treats as a fault.
Late outcomes are the point
There is no window after which an outcome stops attaching. A consultation booked in March and attended in June still credits the click that produced it, and the reports for March restate themselves accordingly.