Combination Bar/Line chart---each with different number of data points
 

I'd like to create a combination column/line chart (no problem there).

Here's what I'm having trouble with: The columns will each represent
data over a calendar quarter (primary x-axis), the line will represent
data for individual months (secondary x-axis); the columns and line
will be plotted against separate y-axes. Visually, the finished chart
should have columns with no space in between, and the width of each
will contain three data points of the line chart. Is it possible for
each chart to have a different number of data points, but graphically
have the same horizontal size?