FLR(FP) first application

Hello everyone, found this board whilst looking for documents that can be used to prove that a parent lives with his/her child.
Hope I am in the right section? I urgently need assistance please.
I applied for the flr(fp) 10 year parent route on the basis of my second son who is British(he is one year old).
I have two sons but I am no longer with their dads.
The application was refused saying that the Gp letter and the red book I submitted is not enough evidence to show that I live with my son( the little one that's British).
His dad also wrote a letter saying that I have sole responsibility for my son that we are no longer together but he has two signatures and the signature on the letter he wrote was not same as the one on the ID he gave to me to submit.
Please what other kind of document can I use to prove my son lives with me because his Nhs letters I submitted from his birth according to them are outdated and appointments now are done on phone. Would appreciate any quick help because my appeal documents will be handed in tomorrow.
Thanks in advance.

For tomorrow its probably just a case of what you have to hand in the house.
Dodgy letters from relatives won't carry much weight.

Ideally you could use:
court order;
PRA document;
social services documents;
medical registration letter/NHS number;
NHS Summary Care record;
GP/dentist/clinic letters;
vaccination record/certificate;
medical prescriptions;
pharmacy registration card;
nursery/childminder /(school) letters;
benefit letters;
Child Benefit letter.

Thanks @noajthan, this was really helpful.

I know it is late but like noajthan, I had some papers at home that I didn't know would be useful plus I have today to run around,so any more suggestions is welcomed.

Really appreciate the quick reply @noajthan

hay please can u tell me when did apply and when u got refused ? thanks
i apply in 16 feb 2016 but still waiting........