WHY??!!

I think there are many good reasons for sending all of family members' applications in one envelope and still place each application in their own smaller envelopes to ensure that the photos and any supporting documents stay with the proper application. it mentions to send the applications of all family members together in one envelope in the previous guide:
'' If you are applying for passports for other members of your family, send all your applications in one envelope''
Post office check and send accept one payment to cover all of the applications that are being submitted together but they don't accept to send all the applications in one envelope now. Why?!
Any advice is much appreciated.

Already replied here, I dont think rules allow it. But I understand the vent though.