VIsa Extension

[fz15]

Hi,
My Mother in law came on B2 visa and we have filed petition I-130 for her and waiting for the approval. Her 6 months visa will expire in Sep and my question is do I need to file form I-485 & Form I-539 together for visa extension or if I'm filing form I-485 then no need to file form I-539.
Please advise...

[immihelp]

As long as I-485 is filed before the expiration of legal stay as per I-94 form, there is no need to file I-539 form.