If I give her a copy of this post the next time I see her, do you think that her head might explode?
You could - but you're simplifying it.
Please have an expert check this before you use itThe £178 peak return is any train ... £121.60 any train that calls at Didcot. But if you want to go up peak and back peak, same day, on a train that does not call at Didcot, I think the lowest available fare is
£109.10.
* Chippenham to Didcot single, anytime, £27.50
* Didcot to Cholsey weekly season, £18.00
* Cholsey to Paddington, anytime day return, £49.20
* Didcot to Chippenham super off peak single, £14.40 (morning only peak restriction)
Using National Condition of Travel para 14.2:
If you are using a Season Ticket, daily Zonal Ticket, or another area based Ticket such as a concessionary pass, ranger or rover in conjunction with another Ticket and the last station at which one Ticket is valid and the first station that the other Ticket is valid are the same, then the train does not need to call at that station for your combination to be valid.
Then you need to consider if it' better to buy two singles if headed up and back in different time zones (e.g. up anytime, back off peak). See
http://www.mrug.org.uk/londonfares.html (and I have just noticed that Melksham is a pound cheaper than Chippenham on anytime return!)
I do look forward to the day that you can simply tell a system or person what your travel plans are and have them offer you the lowest cost option. Many people get put off by this being a bit complicated!