i am tasked to take over a project that has recently taken off the ground. However, there has been no project plan and we need to create one now. Due to circumstances, I can only fix the next milestone in time and need to arrange tasks around that milestone.
This is fine for future tasks, but current tasks don't align so that they culminate into the milestone, even if they are assigned as predecessors to the milestone. If I assign the the previous tasks to the milestone as predecessors, the milestone is moved.

How can I arrange all the tasks around the milestone?