You can have each persons application in separate envelopes with separate checks enclosed in each of the envelopes. Make you each person's envelope has all the documents required i.e filled 485,biographical sketch if an adult,1-94,visa page on passport,biodata page,marriage certificate,birth certificate,copy of your 1-140 approval notice.
Then enclose all the separate mini envelopes into a bigger envelope and write a cover note stating that you are submitting 485 for your entire family,but each person's individual application stuff is in the mini envelopes enclosed.Add a copy of your approval notice to the cover letter. Don't forget to sign your 485 and sign for your kids if they are minors
