Microsoft Visio - Dealing with Collisions
When adding many milestones, it is possible that the description text of the milestones will run into each other creating a messy look. It is possible to avoid collisions by changing the position of the milestone text.
If you happen to have a colliding text, simply grab the yellow end of the milestone and drag to a separate position, such as the bottom or higher up. You can also angle the yellow end by simply turning your mouse to a desired angle. The idea is to ensure that the text doesn’t collide and is represented as clearly as possible.
Once the yellow end is dragged and released, the Line milestone shape adjusts itself accordingly. You can also use the guides to glue the yellow ends of multiple milestones so that they are all aligned.