Can excess fabric in the lap be reduced? I have two pairs of dress pants that need to be taken in at the waist and tapered a little bit as well as shortened slightly. These pants both have double outward pleats and a 12.5 inch rise. Will the excess fabric just go away when they are altered in other ways?
To answer the first question...
Pleated trousers intentionally contain extra fullness in the lap to do precisely what yours are doing when you sit down!
If you don't want that to happen, you need to have the pleats removed or buy flat fronts.
Again, only loosely take the advice of folks in this thread who are not actual garment technicians. It only creates confusion.