How join army of my different city in only one ?

How join army of my different city in only one ?
When I do "dispatch" the crop copst are transfert too.
I want join all my troup in only one army but each unit keep crop cost to his production's city

Can you help me ?

The crop consumption is specific per city.Whichever city the troops are in is the city it will consume crops from.you can,however,transfer crops produced or bought between cities, to help supplement extra troops.hope that makes sense

tks for the answer. It's ok for me