Unlike any mythical Bolton town centre link there are already pretty developed plans for Stockport routes.
In the early noughties quite well developed plans for a Metrolink extension from E Didsbury to Stockport were worked up. The route ran to Heaton Mersey along the old rail alignment, then crossed the Mersey and M60 to Gorsey Bank. It then ran along the Mersey valley to the town centre, with two more bridges over the river because of the difficult terrain. This extension was eventually dropped from the Metrolink Phase 3 programme. Partly because of the high cost, but also because of the lack of support from Stockport Council. At that time the council was obsessed by impractical ideas for restoring a heavy rail link between Stockport and Marple.
More recently, tram-train proposals for the Stockport area included a route from E Didsbury to Hazel Grove via the freight line through Cheadle Heath, with a new chord to link with Altrincham to Stockport line where these lines intersect in Adswood. Tram-trains from E Didsbury to Stockport would have left the heavy rail line at Edgeley Junction, then run on street to the west of Stockport station and down the hill to the Interchange. A long loop around compared with the direct route up the valley.
TfGM is still proposing the Stockport end of this route for future tram-trains from Stockport to Altrincham and the Airport, but the Adswood chord appears to have been dropped. It would probably have needed private housing to be CPO'd.
The wheel now appears to have turned full circle - the new announcement talks about a Metrolink (not tram-train) extension from E Didsbury to Stockport Interchange (not Stockport Station). Start of construction in 2025 seems too early for tram-train, considering that TfGM strategy is to evaluate three tram-train pilot projects before committing to anything bigger, and that Network Rail would have to be involved in a tram-train project. So it would appear that something similar to the original Mersey valley route has been resurrected. It is striking that there was no mention of Metrolink to Stockport in TfGM's Draft Delivery Plan 2020-25 (linked in post#5), which was only published a year ago. Presumably the change of heart is based on a perception that Central Government is now more willing to fund infrastructure projects in the North.
The eastern end of the proposed route is shown on plans in the consultation draft of the Stockport Town Centre West Strategic Regeneration Framework, dated July 2019:
https://consultation.stockport.gov....90717_master_consultationdoc_print_lowres.pdf. See Figures 24, 27 and 28, which also show the proposed tram-train alignment south to Edgeley.
The design of the new Interchange already makes provision for Metrolink platforms and construction is about to start. From the Interchange the Metrolink alignment would initially run west along Brinksway (see pp.110-123 in the SRF document). I suspect the rest of the route is still at the stage of comparing options, given the 2:1 range of costs quoted and considering that the project is stated to be five years away from start of construction.