First, some rough background information... My office is moving to a new building sometime probably in November, but there is likely to be schedule slippage in either direction before then. My superiors want me to find software that will let them schedule and manage all the tasks required for the move; if possible, they want to be able to view the tasks in terms of relative date where "day zero" is pinned to the day of the move, and tasks would be laid out both before (negative days) and after (positive days) that moving date.

When using OmniPlan, you're able to set a project that uses an unspecified start date and measure in T+ and T- days, which is almost exactly what they're looking for; however, because T-zero is defined as being the project start date, the software throws constraint violations any time a task is scheduled before T-zero.

Is there any way to selectively disable certain classes of violations, and simply say I don't care that constraint is violated, continue operating as normal? In this case, to allow tasks to be scheduled earlier than the project start date (since in this case, we'd be using T-zero to represent a milestone in the middle of the project, not the project start)?