if I understood correctly then you have 2 material (Mat1 & Mat2) in the outbound delivery for Mat1 2step picking is activated at material master level and for another Mat2 2step picking is not activated. Now while doing VL06P you want system to create Group only for Mat1 whereas for another Mat2 you want to create TO from LT03 route
If my understanding is correct then system is not designed to process the same delivery one via Group and while group is active at the same time with LT03
