PRO seems to lack the ability to designate which items are combined/grouped to be within a column in the legend. The option of resizing patches and text to fit does not provide the solution, nor does the check box to keep in its own column.
For example, trying to get PRO to move the precincts boundary under the school district boundary- There is no option to designate voting centers, school dist boundary, and prec boundary to be in one column.
"Keep in single column" does not group the items to a single column and is not a solution.
PRO needs to have the option as found in ArcMap:
People are still making paper maps and still require the ability to manipulate legend items to make them look professional.