i-864 question

[sulph 3]

Hello everyone, got a couple of questions, regarding i-864

first question, My wife has filled in her I-864 and thats all ready to go, my wife dosent earn any income, and for the last few years has been claimed as a dependant on her parents tax returns,as well as my 2 step kids, per the i-864 instructions, she has to provide a statement saying why she didnt file taxes, what proof should she send? her parents havent filed taxes yet this year, but has copies of previous years, would one of these surfice as evidence she was claimed as a dependant?.. or would some form of noterized sworn affidavit from her mother surfice?

second question, our original co sponsor lost his job, but luckily we antisipated this in good time and have a new co sponsor, who makes enough to sponor me, now. she is un married, but her 20 year old ex step child? ( not sure of the terminology) lives in her house, and she claims him as a dependant on her taxes, so that would mean her household size is 3 correct? me , her and the 20yr old?

she makes enough to sponsor 3 people (currently earns 29k a year) but i was just wondering, she has everything we need ready and is overnighting it to my wife today, what she is sending is:

i-864 all 8 pages signed,

W2's and tax returns for 2011. 2010 and 2009

proof of employment

proof of current income ( letter from employer stating her raise from 28k to 29k for 2012)

birth certificate,

a few recent paystubs

i know that she has allready sent the i-864 but page 8 is the signed part, the household size page is able to be emailed to my wife if it needs to be changed, im not sure if it dose, hence the question.. hehe