You could, I think, basically, what you'd need to do is go half way in my guide.

Right at the start where you unmount /home/usr/MyDocs, you'd go into fdisk, remove partition one, create a smaller one, by the amount that you wish to increase the FAT section. Then follow on through.

Then when you go into fdisk later on to change partition 2 to c type, you would first delete this partition and create a new one taking up the whole free space, then follow the rest.