Composite Size Optimisation

Hello!

I have a problem and I haven't solved it for few days already. There is a rectangular composite plate and it is necessary to optimize thickness of the each ply to reach minimum mass and acceptable stiffness. Besides the thickness of each ply must to be multiple of the certain number. But a freesize optimisation with a composite optimisation result to the laminate with plies of different forms and each ply has inconstant thickness. I tried a lot of different ways, but it didn't help. For example, increasing of MINDIM is confined by some average dimension, and inspite of defined TMANUF of plies and PLYMAN of desvar the thickness is not multiple of the number. Can anybody help me?

Best regards