My steps are not quick enough, but a macro or Excel won’t be more convenient/flexible as far as I know.
(Use “Quick Launch” if you can not find the commands used below.)
Select column 1 (by clicking the Column Header above the Ruler).
Copy it. (“Copy Column(s)” command also can be used, when the selection is not the whole column(s).)
Paste it into a new tab.
Now in the new tab:
▲ To insert an empty line between each two groups.
Select the 2nd (empty) column (by clicking the Column Header above the Ruler).
Numbering: (Enable these 2 options)
Skip Empty Lines.
Restart Numbering after Empty Lines.
After the numbers are added, press “_”.
Delete column 1. (Now only the number_ column remains.)
Use “Remove Empty Lines” command.
Select the column (by clicking the Column Header above the Ruler).
Copy it. (Or use “Copy Column(s)” command.)
Now go back to the previous tab:
Position the caret after the 1st tab character. (= before “Mini…”)