Wow, this does get complicated!
I'm not really desperate to go anywhere in a 150, as that is all that runs on my local line (except when a 153 is stuck on the front or rear) just trying to find the cheapest way to get onto the area covered by the Rover ticket.
This "any permitted route" clause is complicated, as none of the options I've looked at show the route via Birmingham. One was even via Droitwich & Bromsgrove.
I've been careful with more than one ticket for "one train" journeys in the past, as I thought the train had to stop at the stations referred to by the tickets. You live & learn.
One thing in my favour is a senior railcard, which probably also explains why I'm trying for the cheapest option.