Thanks for your welcome and reply.
The wing is swept, tapered, constant airfoil and untwisted. I recently came across an equation in Datcom (Section 4.1.4) and also used in Roskam's "Airplane Design" Part 6 which relates the Cm of the airfoil to the Cm of the wing, given aspect ratio and sweep.
Would anyone know about the equation and how it is derived? I don't think it's from lifting-line theory which doesn't give info about force distributions in the chordwise direction.