Change distribution of data points on line chart?

I have a lovely request from my boss... He wants me to make certain lines on my chart have data points only every quarter (but still keep the lines connecting those data points)

I tried having only the data entered every quarter but I have just the dots... No lines connecting the dots.

Is there any way to keep the lines, but the data point markers will only appear every 3 months??

My guess is you'd want to plot to separate series - one that has all the data points that you will only show the lines on the graph, and a second that only has the quarterly data points that you will show only points. When the two series are put on top of each other, you will see what your boss has requested.

Select the chart and then use the Select Data dialog, Hidden and Empty cells.

Make sure the Connecting line option is selected.

Or replace the empty cells between data points with the function
=NA()