Blimey, that's hard to understand.
You appear to be asking if a London to Manchester ticket routed Any Permitted is valid via Sheffield? The answer of course, is yes. (though it is generally cheaper to buy the Route Chesterfield ticket and an excess to Any Permitted for the portion that you are going via WCML)
But you also appear to be asking if a London to Manchester ticket routed Any Permitted is valid via Doncaster, so that you can avoid having to take the MML route and can use the ECML to Doncaster? Unfortunately the answer is no.
If you wish to avoid Sheffield, you could try to obtain an over-distance excess to Huddersfield (route: Any Permitted) which would then be valid via ECML to Doncaster.
If you have not already purchased your tickets then perhaps you can reveal details of all the applicable journeys you need to make as we can probably find a cheaper combination of tickets.