withdrawal of 221g application and Filing New H1b amendment

[blackpearl77]

Hi Attorney,

I got my H1b approval in Sep 2016 and attended Visa stamping after a month, But since I could not produce client letter i was issued 221g slip and my visa was denied.I have still not provided any related documents to consulate.

I had H4 stamped earlier and hence traveled on h4 starting of 2017.

I have found a project now and my employer wants to file new amendment for new client. Before filing new amendment, he is asking me to send a withdrawal request for 221g visa application through mail to consulate..

Queries:

Is it mandatory to withdraw the 221g application and then file new h1b amendment?
If yes, In this process can my H1b approval itself be revoked?
Is there any affect to my current h4?

Is there any timeline to apply for new amendment if the 221g withdrawl is done sucesfully?

Please advice