Couple places you can do this:
a) In the Order Notes section
b) As an order tag
I like doing it as a tag, because then it will be searchable later on if you need to pull up the order based on serial number.
Thanks a lot for sharing.
I did think about these workarounds:
1, Order Notes: might not always be available, customer could already used it, e.g. for VAT number, PO number.
2, Order Tag: Tag by the meaning of it, is to categorise or attach "attributes", e.g. "Have_Serial_Number" is a good tag, but serial number is a concrete string, not really useful to "categorise" anything. I do agree that Search is a benefit.
I'm also using Timeline to just add a comment line for the sn. Apparently search doesn't work here.
So I was really hoping to have something similar to the Add Tracking Number stuff, make it much more formal. Would be even greater to be able to see this column in various reports.
Thanks once again,