I just got my I-140 approval and based on that I am going to file for my H1B extension and H4 extension for my dependents.
But, I don't know what documents I need to attach for the H4 extension since I don't have my H1B approval (I-797) as I am going to file my H1B based on my I-140 approval.

I have these following questions related to H4 extension:
1) Do I need to attach the I-140 approval copy with I-539 form for the H4 extensions?
2) Do I need to attach the old H1 approval copy (I-797 copy, which is going to expire in a month)?
3) What other documents I need for the H4 extension?