Mergers on an Excel Timeline
This chart is a good solution for showing a macroview of merger starts, progress, and completion. Notice how a line for an activity changes trajectory and then merges with another activity. In this chart there is a main activity into which subactivities merge, but you can set it up any way you want. Using an Excel line chart as the basis for this type of chart keeps the lines equidistant and makes editing easy. No alignment or distribution headaches when the chart needs to be edited. Dates can simply be changed in the datasheet for the line chart. If you need more detail, you can plot the timeline in days, weeks, months, quarters, etc.
The example below shows how to set this chart up. There's also a download of the chart for you to review.