Hi Livonia
I have not yet completed an online electronic form yet.
I would use the new guide, it does not matter when your original claim was made.
If you cannot use PDF then I would contact DWP and ask for a paper version.
If you are using the electronic form then add extra pages as if it was a paper form, make sure that each extra page has your name and National Insurance number on them.
If you kept a copy of the original application form then use that as a template, don't forget to upload any supporting documents including one from your son if he does any caring for you.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems