can I file i-485 for my brother while his i-130 is still pending?

An I-485 adjustment of status application requires that the priority date be current at the time of filing. For the month of February 2020, U.S.C.I.S. is using the dates of filing chart which is currently up to 7/22/07. Therefore even if your brother was here, he would not be eligible to submit an I-485 application. I do not see that there is a long-term visa available to your brother to help take care of your elderly parents. He may be able to apply to come to visit them, but that would be pursuant to a visitors visa. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.