My son, home for the weekend, has the return portion of an Off-Peak Return Cardiff Central to Altrincham, which was supplied by his company. He wants to return direct to Cardiff Central from home (Parbold or Wigan stations) either tomorrow or Monday. We assume that he should join the route at Stockport but were wondering if he bought a single to Crewe from Parobld or Wigan he could join the route there and save a lot of time going over to Stockport. Is this a valid and quicker way of getting back to Cardiff? Thank-you in advance. In this case faster rather than cheaper is the primary goal.
If he's going to Parbold, it's quicker to change at Stockport - and it will be an easy cross-platform change. If he's going to Wigan, it's quicker to change at Crewe.
His ticket to Altrincham is
technically not valid to break his journey at either Crewe or Stockport, but this restriction simply won't be enforced in any way, and your son should feel quite comfortable in just buying an additional ticket from Stockport or Crewe (depending on which route he takes).
He could try to get an overdistance excess to Parbold/Wigan at the ticket office (the fare is actually about £1 less than that to Altrincham!) but it's quite likely they will be unable to do so.