Hi Maz,
I use Family Tree Maker, rather than Legacy - it came free with a Sunday paper and being a true East Coaster.........
An example of how I record it [which I appreciate might not be much help!] is:
My great grandfather was born in 1890 at Braidhurst Pit Rows in Motherwell, and this is recorded on the birth certificate as Braidhurst No 1. In the birthplace box on FTM I have recorded
"Braidhurst Pit, Motherwell"
The
'official' bit of the certificate records the birth as taking place in the Parish of Dalziel in the County of Lanark. In FTM there is a 'Sources' section which you can link the Birthplace/Marriage/Death information to, so I have created a source for my great grandfather's birth:
"1890 Births in the Parish of Dalziel, County of Lanark"
and noted the SP parish/county reference after it so anyone else using my information could find it and to differentiate it from any other birth I have recorded in the same year and place.
I don't know if Legacy uses sources in the same way.
Like you, I find that the Parish/County info isn't specific enough for the actual birthplace and I quite like to see the names of the pits/farms/etc listed through the generations. It's also much easier when printing out trees and reports, as FTM can add the full source information as footnotes, which cluttering individual boxes with the full blurb.
FTM can also pinpoint locations on a map - but I've never used it, so have never felt the need to be map-specific with my references.
Best wishes
Brian