No Problem, I hope the project goes well.

I have replaced the discoloration you speak of on a job before & the doors just a few months ago. Basically we will use a motorized saw at a horizontal angle and cut about an inch above the rot line all across to remove all of that. Of course make sure the interior allows this & does not have flammable fluids stored against the wall inside or wiring where you cut. (Gasoline Cans or Bug Sprays etc) as a power tool will surely ignite this. Then we just cut and place new wood. I would also consider staining the entire structure with water sealant stain and perhaps even siding it with vinyl if you want to make it last considerably longer without having to make patchwork fixes very often or ever again.