Can the I-601A and I-140 be processed concurrently? can they be filed at the same time.

After 9 months my PERM (employment based) finally got approved (this after the immigration firm took about 1 year to put it together and then it got audited. Now, they will file the I-140 and then they will do the 601A. They refuse to start anything related to the 601A unless the I-140 gets approved. They had not mentioned anything about the waiver until I asked. Is there anything I should be doing to get this ready or I should be asking them to do. I an unmarried daughter (over 21) of a green card holder (my mother).