[Lizard]

If you're using Outliner Standard, remove 'Professional' from the first line.
And if you just want the three rows to be added after your selection, trim it down to:

tell application "OmniOutliner Professional"
	set MyDocument to front document
	
	try
		-- If there is a selection, add our new rows underneath it
		set MyParent to last selected row of MyDocument
	on error
		-- 'last selected row' will raise an error if there are zero selected rows; add the new rows at the top level in this case
		set MyParent to MyDocument
	end try
	
	tell MyParent
		make new child with properties {topic:"Roll"}
		make new child with properties {topic:"Review Agenda"}
		make new child with properties {topic:"Approve Agenda"}
		set expanded to true
	end tell
	
	
end tell