H-1B Visa

I'm working on H-4 EAD with company A. Company B filed for H-1B for this year and it was picked in lottery but no decision made yet, now I don't want H-1B and asked company B to withdraw the H-1B and he agreed to it and shared the H-1B withdrawal letter along with the I-129C notice. Just to make sure that the petition is withdrawn without any issues, can I also post the same letter again to USCIS with company's from address on it?

I am currently on L-2 EAD (since Jun 2017) and work for Employer A. Can my current employer (Employer A) file for my Green Card ?

I have the following questions<br>
Can employer A revoke my current I-140 after I change my employment?<br>
Can I keep getting my visa renewed with Employer B based on my current I-140 with Employer A until Employer B initiates my GC processing?<br>
Does the hike in pay and change in roles in any way affect any of my future GC filings with Employer B?

My spouse and I are staying in the USA since last 10 years on work visa H-1B. We have our second daughter born in 2016 who is facing neurological disability which requires long term care and constant therapies. The current scenario is my husband's H-1B has denied and couldn't get back to the USA. I am here in the USA with my both kids on B2 Visa. My both kids are US Citizens. Is there any legislation which can provide legal stay to the parent of a child with disability in the USA?

I have my I-140 approved in 2015 and its beyond 180 days now with Employer A.
<br>
If I move to Employer B
a) Consider that Employer A revoked my I-140<br>
b) Please help to confirm will it possible to get multiple extension with previous 180 approved.<br>
c) Even if Employer B doesn't file a Green Card (Labor then I-140)... Can I get multiple extension with Employer A approved I-140

I am on H-1 Visa and my son is on H-4 visa. He is 17 years(studying 11th grade). I wanted to know whether i need to change the visa status at the age of 21. If so, the green card processed by my employer for him will still be valid or not. Also, if he goes to India for studying his degree for like 4 or 5 years, will the green card processing for him will be valid.