Hi -- I found this script useful. But I wanted to be able to convert ALL child rows to notes of their first order headings. So (mostly through trial and error) I modified Rob Trew's script to do this.
This script should start at the beginning of your document, and convert all child rows, of whatever level, to notes of the first-order headings that precede them. I would recommend trying this on a copy of your document first, as I am an absolute beginner in Applescript.
-- provided AS IS by Rob Trew, with minor changes by SG
-- collects topics and notes of children of selected line and places in note
-- IF YOU REALLY WANT TO DELETE THE CHILD NOTES
-- THEN CHANGE THE VALUE OF THIS PROPERTY TO TRUE …
property pblnReallyDeleteDescendants : true
-- Modified by Gregory MacIsaac (June 2017) to do the same for all first order headings in a document -- as written I have left 'delete child notes' to true
tell application "OmniOutliner"
tell front document
set rowCount to count of rows
repeat with i from 1 to rowCount
tell first item
set lstSeln to selected rows
if length of lstSeln < 1 then return
tell first item of row i
if has subtopics then ¬
set its note to its note & my GetSubText(its children)'s text 1 thru -3
set its note expanded to true
tell application id "OOut"
set str to ""
-- CAPTURE THE TEXT
repeat with oChild in lstChiln
set str to str & its topic & return & its note & return
if has subtopics of it then set str to str & my GetSubText(its children)
-- AND THEN DELETE THE CHILDREN ?
if pblnReallyDeleteDescendants then
repeat with i from length of lstChiln to 1 by -1
delete item i of lstChiln