WCML local services

Watching a class 350 speed past Motherwell today made me think: Some Virgin trains stop at Motherwell, but Transpennine Express do not (weirdly their Edinburgh services do call at Haymarket). You would think the slower, more "local" TPX trains would stop at places Virgin's Pendolinos do not. Same for Carstairs. (Transpennine Express do call at Lockerbie.) If Beattock station gets rebuilt (as is the aim of the Beattock Station Action Group), whose trains will call there? If I were in charge of the network, I would put Transpennine Express in charge of stopping trains, calling at the intermediate stations on the route (Motherwell, Carstairs, Beattock and Lockerbie), and have the faster/longer-distance Virgin trains going non-stop to Carlisle.