You can put it all in one envelope and just clip each section together to keep it organized, or you can put it in three separate but clearly labelled envelopes and then put all three of those in one package for her to send out. I really don't know what they do with the packages once they open them and if it makes any difference or not if you send it all in one envelope or divide it into three, I think as long as it is organized and clear that you have included all the necessary forms and documents you should be ok.
For any forms where we couldn't fit our answers in the space provided, we attached the additional sheets to the back of the corresponding form with a paperclip, and then wrote something like 'please see attached sheet' in the space they provided so they knew the answer would be on another page. Just make sure you clearly label on any additional sheets which form and question you are referring to, and it's also a good idea to include your name and date of birth on any additional sheets in case they get separated from the form they are attached to.
