can we submit two I-485 together, one is employ based, one family based?
-Yes, but you don't need to file two I-485s, and just file one I-485 based on I-140 or I-130, then ask USCIS to do the I-485 relink (i.e. interfiling) to another petition of I-130 or I-140. Thus, USCIS will approve your I-485 based on either I-140 or I-130, depends on which the priority date is current first.
Would denial of one affect the other? -No.
The goal is for the interest of time to get green card faster rather wait if family based is unsuccessful then try the employ based. many thanks.