Hi Oxa,
Thanks for noting, hopefully a few others might find such a feature useful!
As an alternative, would it be any easier to implement new market prefixes? I was thinking having the option of *only* markets might provide a workaround for most of the cases where per selection per event might be needed. For example, eachwayonly_back_price would refer to the selections back_price in the eachway market from whichever market of the event it was called from (including eachway). Similarly, winonly_lay_price would always refer to the selections lay_price in the win market. Having a fixed target would allow calculations for horses in one market to be run from any of the events markets without tripping over the opposing/reciprocating winplace_ and eachway_ prefixes (this wouldn't be an issue with football, as football market prefixes always refer to the same target).