My understanding is slightly different than Darryl’s. When “Show For…Tasks” is satisfied for a given task, then all the satisfied bar styles are layered one atop the other for that task – with the bar style shown last on the list displayed on the TOPMOST layer.
So to get what Perry wants, 1. Assign a new custom Start (say Start10) to the task – representing the date when the new bar style should take over. 2. Add a new bar style at the bottom of the list, formatted as needed – From “Start10” to “Task Finish.” It doesn’t strictly need a “Show For…” filter as long as you intend to show the bar for all tasks (and only those tasks) with a value in Start10.
The new bar lays on top of the later part of the normal bar. Done. Good luck, tom