The shortest route Kidderminster - Swindon is fairly obvious:
Kidderminster - Worcester
Worcester - Cheltenham
Cheltenham - Swindon
The fare Kidderminster - Swindon is £30.50 Any Permitted
This fare is set by XC, although it's difficult to see how you would use XC on this route.
The associated routeing points are Smethwick and Worcester. Smethwick is further away and unsurprisingly more expensive fares and therefore not a valid routeing point.
Worcester Stations or Droitwich -Swindon is
£38.50 Any Permitted
£20.90 via Stroud
The relevant comparison is with the Any Permitted fare.
Accordingly Worcester is NOT a valid routeing point, the only permitted route is the shortest route or routes up to 3 miles longer.
The only valid route is:
Kidderminster
Hartlebury
Droitwich Spa
(Worcester Foregate Street)
Worcester Shrub Hill
Ashchurch
Cheltenham Spa
(Gloucester)
Stonehouse
Stroud
Kemble
Swindon
So from Wolverhampton you could travel
Wolverhampton - Smethwick G. B.
Smethwick - Worcester (via Kidderminster)
Worcester - Cheltenham Spa
Cheltenham Spa - Swindon
with a Wolverhampton - Kidderminster ticket plus your Kidderminster-Swindon ticket.
Other more direct routes are unfortunately not permitted.
