I think the PDL: Waterloo - Portsmouth needs the line down to Alton from both the SWML and PDL Side like the old one did
Yes, the original PDL Woking-Portsmouth had quite a network of bare-bones track and landscape. I believe the extended Waterloo=Portsmouth used that as a base. So it could be possible that routes could be added to Alton and elsewhere. As an aside, I've used the original PDL to make a backdated 1950/60s line between Guildford and Redhill. Screenshots below. https://steamcommunity.com/profiles/76561198097011976/screenshots/