[zopepaul]

I also had the same goal. Not yet familiar with OmniPlan, I took a shortcut and typed up a bunch of data in OmniOutliner. I dreaded the cut-and-paste and postponed it until it was a whole bunch of info.

I was surprised when I tried to do an import and it worked. I opened OmniPlan, did File-Open, saw that it recognized my OmniOutliner file. When I selected that, it asked me for some mapping information for columns -> columns.

The resulting OmniPlan file had grouping correct and mapped 0 effort tasks to milestones.

There was only one thing it didn't handle. My Assigned column was a Popup List in OmniOutliner. It didn't map the string values from that into resource creation and assignment.