It will still be charged for each applicant but you'll have to argue with them about the letter. Individual letters are for TRVs, not PR applications.I got a single letter for my parents and when calling VFS (Australia) they said they can only accept one passport with one letter. Looking at other people complaining, maybe VFS is just trying to make a quick buck as each submission is $60+.
Anyways, could @Mr.Nurse or @winterc11 please share how they submitted their passports?