We're in the process of renewing my husband and DS1s passports and applying for DS2s first passport. We need to send the old passports and DS2s birth certificate to them but I noticed the address to send to on the confirmation page includes the application reference number. We'll send recorded delivery, but does anyone know if I can send on one envelope (with separate envelopes inside for each application) to reach some postage costs? Or does this have the possibility of screwing things up/causing big delays? We're not going away until August but I'd like to get them in hand well before then!