H1B 7th year extension and amendment

[Bahubali]

Hello,

I am in 6th year of H1B (expiring September 30 2017) and in the process of applying for extension through company A and client A. I am unclear about the project duration at client A. Once I applied for extension through client A and while status is in pending and my contract at client A ends, will I be eligible to file for amendment through company A and client B?

I believe everything will be good if my petition is approved before contract at client A ends but what if I got a query with client A and by then my contract ends?

Thank you.