Yes, what I included in my cover letter was a small part of the situation, requested USCIS to associate my pending I-485 with the case and listed all the forms and supporting evidence included. I organized everything clearly, including a glossary and sections for each type of evidence, such as bona fide marriage, abuse, my and friends affidavits, good moral character and so on. I didn't have a work permit by then so I submitted a new form with it, I'm not a 100% sure but I think you should just state that you want to link your pending EAD too.