You need to send all 4 pasports for stamping in separate packages. Here is my guide 
for ppl who are not visa exempt:
0) take photocopies of passports for record
1) take 2x pictures for each person, label each on the back:
    name
    dob
    app. no.
    photo studio
    address
    date taking photo
bring tape & specs to check before paying photographer
put each photo in a small envelope, on envelope: name, dob, app. no.
put both small envelopes between passport pages
2) go to bank and order a cashier check of $22.8 for each person:
    (optional) with SMS fee: $22.8 + $2.5 = $25.3
    recipient: VFS Services (USA) Inc.
    Memo: transmission + SMS fee
3) print passport request letter for each person
    fill out the appendix table for the whole family
4) go to VAC website provided in passport request letter
    check if there are any updates
    create new FedEx label order at 
https://www.vfsglobal.ca/PostalAppointment/Home/Index
    fill out info for each family member
    pay online
    download and print confirmation letter & shipping labels
5) print 2x consent forms for each person:
    sign page 2 & 4
  
6) put everything for each person in a separage package:
    include an page: name, phone, address, email
    glue shipping label outside package
    superscribe envelope: ORIGINAL PASSPORT SUBMISSION -- Indiv. Ref. No.
7) Go to FedEx:
    use paddled envelopes, throughly seal
    bring pen, glue/tape, scissors, evelopes
    drop off and confirm tracking