Yes, mailing fee would be separate for OCI and SC.
I will be picking up OCI in person; so did not send mailing fee. otherwise, it would be 20+1+1+<$1>. I think it is only two adults + two children, then it goes to 20+etc.
For surrender certificate, we did send mailing fee with SC fee ($175 ($155 SC fees + mailing fee of $20) for each person, two separate Money Orders in my case).
Fee structure would be :
OCI : $275 (OCI Fee) for each person + $20 for first applicant and add $1 for each additional applicant (upto maximum number of applicants allowed) -- Separate Money order, separate envelope
Surrender Certificate : $155 (or $20, depending on when one became citizen) + $20 mailing fee. -- Separate Money order for each person, separate envelope (you can put as many applications as possible in one envelope)
In my case, Chicago consulate sent both cancelled passports and SC in one envelope, guess they made $20 profit.
