I'm a chart neophyte.

I have a worksheet with multiple line charts, each line depicting total
hours per month per project.

I would like to align the lines to a common milestone, like "start of
detailed design". Each project of course has a different date for this
milestone.

Other than knowing that somewhere I'll have to specify the dates of the
milestone for each project, I have no idea of what to do.

Any help/insight will be appreciated.

Thanks,
Mike