Finally got ceremony done and now applying for passport

We are 3 members of the same family applying together via online method. It created individual application refs for each of us and now I have to send supporting docs, I want to ask if it is possible to send documents for all of us together in one envelope?
As the address to send documents has application ref, is it possible to list all three reference nos to combine these or just avoid the possible confusion/delay ?
Thank you very much for all the help!