It's definitely going to be the best way from Wolverhampton to Halifax on a frequent basis, and it's bananas that it's somehow not permitted.
Do you want to get the route added as a mapped route for Wolverhampton to Halifax? Or do you want to be able to use a through ticket to travel that way? Or do you want to travel that way at the best value for money?
If you want to get the route added as a mapped route, that could be difficult officially (although it may be picked up now that it has been posted here, but for positive changes I would not hold your breath). You could try writing to CrossCountry, who manage the fare, or to Virgin Trains or Northern, whose train services you would be making use of. If you want real success you may need to try all three. You could also try polite emails to
[email protected] and
[email protected] but I doubt those mailboxes would be read by people who understood the nature of your request. If you are serious about this the only real thing you can do that has a reasonable shot of success is to write to your MP. Ask them politely to get in touch with RDG and the train companies to request this route is added. Letters received on House of Commons stationery are likely to be read and responded to in a mature way, although often not in a timely one! Give your MP as full details as possible, as their staff might not have come across this sort of case before. You will want to mention that the route Manchester ticket is the one you intend to use for your journey via Warrington Bank Quay.
If you want to buy a ticket and just go that way, you could try the booking office at your station (or any station). Download the National Rail Enquiries app and put in Wolverhampton to Halifax. It suggests one change at Warrington Bank Quay by default. If you show the app to the ticket office staff and say you'd like to make that journey, and ask them to provide a suitable ticket, they will probably sell you the through ticket. You are then permitted to use it that way regardless of anything else. Many ticket office staff are happy to ignore the routing guide in the face of common sense. Many don't even know it exists. You can specify to them that you want to make a journey with no more than one change. If you pop into the ticket office before the day of travel, they can probably provide you with a seat reservation between Wolverhampton and Warrington Bank Quay which you might find useful.
If you want a cheaper way to make the same journey on the same trains changing in Warrington, I recommend
raileasy.trainsplit.com put it in and see what you get.
PS the above represents some answers to your implicit questions, and I hope some reasonably practical advice, but one other thing you can do now but may not be able to in future is just use an online journey planner that has low accuracy e.g.
https://ticketsbeta.c2c-online.co.uk will actually let you do this journey via Warrington Bank Quay with a through ticket, so you could just book it there and then you are sorted. Of course this might get fixed at any time!