OK - here's another one. I'm looking at a RTW that requires a 14-day minimum between DEP and ARR. It is 35% of the cost of a ticket with a 8-day DEP-ARR gap which is how long I need to be away for business reasons.

Would it work for me to add another segment, close to home, get there after the days, take a spearate flight / drive whatever home and then go back to finish off the ticketed trip post-14 days? Is it illegal / immoral?

The routing I'm thinking of is LHR-SFO-NRT-LHR and changing it to LHR-SFO-NRT-CDG-LHR and taking the Eurostar home to London and then back to Paris to finish the trip off.