At the moment it is only possible to connect a goal to all of the milestones or tasks in a project. This is not useful when you have several goals focused on a single project - as is often the case. It would be much more useful if you were able to select the specific milestones from the connected projects that you want to be counted towards that goal.
The workaround at the moment is that you just create sub-goals instead of using milestones, but the disadvantage of that is that these sub-goals then do not show up under the project’s list of tasks and milestones so they are not very useful operationally.
It would be much better if, for example, you could create two goals linked to a specific project, with three milestones each (6 milestones in total). And then you could connect each of those goals to its respective 3 milestones only so that progress against that goal is automatically updated when you make progress on those specific milestones.