New a worksheet and import \Samples\Statistics\automobile categorical.dat
Highlight Col(C) and Col(D) to open grouped box plot dialog.
Set Grouped Plot By as Col(H) and Col(I), Multiple Data as Overlay on Same Graph. Click OK.
==> The tick label N for Korea and Sweden are merged. Y for Sweden and Germany are merged.
Origin 2025b SR1 add a checkbox All Combinations for Groups after Multiple Data, show it only when number of group columns>=2. Select this checkbox, Origin will add empty column when there is no data for group combination.