Yeah, we sent the I-130 and the I-485, and all necessary documentation and forms, in the same envelope to the Chicago Lockbox. We used one binder clip per form to clip the form and the evidence for the form together. We also included one check in the amount of $1365 payable to US Department of Homeland Security to cover both the I-130 and I-485 fee. (Sending one check is optional and most people send two, one for each form.) We also sent G-1145 to receive an email on when the applications where accepted by the lockbox. The emails came a week after mailing the package, and the official receipt notices came in the mail five days after the emails.
Sorry, I though you where questioning the law.