Price on real availability, current cost and your margin targets.
Add a Senior Engineer for the quarter and set a day rate. Name someone, and their cost comes from current salary or contract rate while their availability is checked against other work. Leave the role open, and it carries the cost your firm set for it. The blended margin recalculates as you go, against the target for how the work is staffed.
When delivery later changes a row, the outlook moves the same day.