Phase-completion triggered billing in payment schedules

I like to bill periodically after certain construction phases are complete. The current payment schedule only supports due dates of On Approval, On Completion, or Specific Date — but there is no option to tie a payment milestone to the completion of a specific construction phase. Ideal workflow: define payment schedule entries linked to construction phases (e.g., Foundation, Framing, Drywall), and when that phase is marked complete, the corresponding invoice becomes due automatically. This is a common billing pattern for general contractors who do progress billing based on phase completion rather than fixed dates.