Impossible to condense two harps?

Is there a reason why Dorico would not allow the creation of a custom condensing group including two harps?
This is good in operas when the two harps are playing the same, and the label shows “2 Harps”:

Is there a way to do this that is not a hack?

Not currently possible, I’m afraid:

Only instruments that normally have a single staff and whose music is in a single voice can be condensed, as music already in multiple voices produces ambiguous condensing results. Grand staff instruments cannot be condensed. Instruments with extra staves or ossia staves cannot be condensed in the systems where the extra staves or ossia staves exist.