Writing Odometer confusion

[smwaverider]

going to increase miles on dash lcd as bought a replacement cluster with lower miles. (lcd display failed).
A bit confused, my mileage displays in miles, but it is KM on ecu's. When I enter the write odometer function on the Marelli Display, do I need to enter the correct distance in miles or km? I am scared of writing the larger km amount if that figure will then display on the dash, as miles?
Could administrator please clarify before I do it?
Thanks,
Steve forgot to say, it is a Fiat Grande Punto. Also, should I write new mileage before or after Proxy Alignment (needed because of replacement, secondhand cluster)?