If the plan is to extend Chat Moss services this way (to free up dwell time at Victoria) then its just going to cause congestion again.
Hence why I'd give the Chat Moss lines some bays on the Exchange Campus, the only through services through 3/4 at Victroria being TPE (4tph) and Calder Vale to Airport (2tph).
5/6 handling everything to Windsor Bridge (Currently also 6tph, possibly incresing to 8tph) 4tph of these sent on to Stalybridge (flighted behind fasts), and 2tph sent on to Rochdale. (The Diesels)
The 2tph TPE Semi Fasts go into Piccadilly, and the 1tph Super Slow Leeds via Brighouse and additional Toddy Curve service terminating in 5/6 or combining onto the Diesels though Atherton.
EDIT:
4tph from Bolton sent on to Stalybridge, electrified (Allows for Electric services from Blackpool, slows from Bolton to run onwards)
Everything from Atherton sent on Rochdale (Possibly forming the Calder Vale & Brighouse Super Slow & Toddy Curve services)
Any additionals from Bolton sent on to Rochdale.
With 6tph on each platform, allows a 4min dwell time and the 'slows' to stalybridge can be flighted to depart 1 or 2 mins after the fasts, fitting the Calder Vales through to get a 15min frequency over the curve and between Leeds and Manchester would mean some skewed timings, for example the departures off Platform 4 and 6 looking somthing like...
xx:00 Leeds Fast From Curve
--xx:02 Stalybridge From Bolton
xx:12 Leeds Fast From Liverpool
--xx:14 Stalybridge from Bolton
xx:16 Leeds via Calder Vale
--xx:18 Blackburn via Rochdale and Todmorden from Atherton
xx:30 Leeds Fast from Curve
--xx:32 Stalybridge from Bolton
xx:42 Leeds Fast from Liverpool
--xx:44 Stalybridge from Bolton
xx:46 Leeds via Calder Vale
--xx:48 Leeds via Brighouse and Rochdale from Atherton
Semi Fasts to Leeds from Piccadilly of course... Timed to arrive at Stalybridge just before the fasts and leave flighted behind them...
Would leave platforms 1 and 2 as being absolutely uselsss, but if Electrification does reach Stalybridge it allows all the services coming from Bolton to be electric when Lostock - Wigan - Southport gets done, some extra tph may be nessesarry, but the preference would be to have all electrics to Stalybridge at 4tph flighted behind the fasts, and then the Blackburn being sent onwards to Rochdale.