Create a "Between" task predecessor

No task duration type, constraint type, or predecessor dependency type allows Project Managers to create tasks with variable durations. We have several instances where task A and C are set dates and task B falls between them. This duration can be 50+ business days and changes as task A and C move based on external factors. This also happens so frequently and in different workflows that a Fusion scenario isn’t feasible.

Ideally Workfront would have a new predessor type that drives both the start and end date independently instead of depending on a planned duration. Task B planned start date starts when Task A’s end date finishes and Task B’s planned completion date finishes when Task C’s start date starts.

The current work around is to set fixed dates for the task and manually update them as the other tasks recalculate but that takes a lot of diligence and effort on the project manager.