I think 子单号 = receipt stub and 母单号 is the main reciept itself used for internal purposes for the company.

how to say "子运单号 and 主运单号" in english?

I felt a little confused about some words recently, such as "子单号" and“母单号".
I am pretty sure that child shipment is a totally wrong chinglish expression of 子单号, but i just don't know how to say it in native english.
A运单号和B运单号是C运单号的子单号。Tracking number A and B are the sub shipment of tracking number C.
母运单号： main / base / primary /master tracking number?????

Pls help,, which one is correct? or all the above expression are wrong?