Hi Ves
I'm sure the DWP will let you swap if you inform them.
However, if you want to continue with your paper application and you want to add additional pages, you can do so. (A lot of people do). Just make sure each additional page is marked with your name and national insurance number, the question number and whatever page number you assign to it.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems