Go to Related Record [ From table: “ORDER”; Using layout: <Current Layout> ]
should be replaced with:
Go To Related Record [Show only related records; From table: Lines; Using layout: "Lines" (Lines) ]
You want your replace action to work over the founds set of lines records, not your current found set of Orders records.
And you should not use Replace field contents when the No button is clicked. Instead, a set field step should be used so that only the current order record is updated.
Sweet, You are a genius! Thanks Phil