Would affidavits be accepted as only proof?

[shouldi 0]

I crossed the border illegally on June 2, 2007 at the age of seven. I have no proof of being in the US until I started elementary school on August of 2007. When we came here, we came and stayed with my uncle until we could afford our own place. However, my dad was already living in the US before my mom and I crossed. My question is, can I get an affidavit letter of them saying that I was here before June 15th?

[ViK 7]

On 6/4/2017 at 8:29 PM, shouldi said:

I crossed the border illegally on June 2, 2007 at the age of seven. I have no proof of being in the US until I started elementary school on August of 2007. When we came here, we came and stayed with my uncle until we could afford our own place. However, my dad was already living in the US before my mom and I crossed. My question is, can I get an affidavit letter of them saying that I was here before June 15th? 

https://www.uscis.gov/humanitarian/consideration-deferred-action-childhood-arrivals-daca Look in here.