Create markers on a line chart on Power BI

Hi Mark_Berry 

How is your Dataset set up? Is the visual above over time?

Are you using a star schema? If you are and you are using the Data from your date table for the time reference in the visual, you could create a seperate table for the Events of Milestones. 

Create a one to many relationship between the date in your date table and the date in the new table. Create a Line and Bar chart, the data you have already goes into the Bar values and the Type ID goes into the line values. You may need to activate the secondary axis for the line chart. There a few Markers available and if you add a legend of the Type to the visual, you can pick and choose what colurs these Markers are

Thanks

Joe