Originally Posted by Chiller3333

It might be cheaper to book this as an open jaw (EDI-ORD, NYC-EDI) and book ORD-NYC separately, as a lot of BA fares include a sizable charge for stopovers in the US.
Since you'll have a buffer of a few days on either end, there is relatively little risk in that (and might explain why Skyscanner is much cheaper, if they issue this on separate tickets).
The daytime flight followed by an overnight not showing is pretty "normal" (as normal goes for the mess BA.com is).