Sending multiple passport applications (for spouse and children) in one envelope

[rubyracer2]

Hi everyone,

I’m applying for passports for my children and my spouse. We are all naturalised citizens and have individual PEX numbers. I wanted to check if it’s acceptable to send all the supporting documents together in a single envelope, mentioning all three PEX numbers on the outside, or if each application needs to be sent separately.

Also, I’m planning to send our documents in a A4 “Do Not Bend” envelope and want them to be returned in the same kind of envelope, but I’m not sure how to fit one of the same size inside the main envelope. Has anyone found a practical way to do this?

Thanks in advance!