It sounds like you are trying to force dates but still want task dependencies. The whole point of creating a linked network is to allow Project to help schedule the plan based on estimated task duration and task interaction.

One thing you might consider is to set up the plan with your pre-defined dates with no task dependencies. Then set a baseline. Now, add desired dependencies. In the Tracking Gantt view you can see the impact on dates (baseline versus current plan). If things don't line up then either the pre-defined dates are "premature" or the dependencies are not valid.

It sounds like you are trying to force dates but still want task dependencies. The whole point of creating a linked network is to allow Project to help schedule the plan based on estimated task duration and task interaction.

One thing you might consider is to set up the plan with your pre-defined dates with no task dependencies. Then set a baseline. Now, add desired dependencies. In the Tracking Gantt view you can see the impact on dates (baseline versus current plan). In particular, the Variance fields (Duration Variance, Start Variance, & Finish Variance), definitize the differences. If things don't line up then either the pre-defined dates are "premature" or the dependencies are not valid.