Uniformalty distributred loading from WCS

Hi

If from load plan I have total load (kN) over an area and area (m2) known and if I convert the loading into area loding (kN/m2) then how do I take care of centre of gravity (cog)?  Area loading will give cog in the middle of are while load plan cog can be off centre. How to take care of this discrepancy. I would like to apply the loading as UDL to the beams while modelling rigid arms (as someone suggested earlier) will require huge number of nodes!!!

Please suggest.

Thanks.