Word - advanced numbering question

Question

Hi guys,

I have the following problem I'm trying to solve. This is for a specification document.

I'm want to list various requirements in the following format:

[Cust. Req 1] Additional field in database
[Cust. Req 2] Background color blue
[Cust. Req 3] Interface to Amazon

I can get all that done using a new style, also the numbering works.

Now here's where I am stuck:

For each of the requirements, I want to have a custom style [Prod. Req xxx] which describes the technical implementation of the requirement. The numbering should match the corresponding "Cust. R" entry.

So, [Cust. Req 1] should be linked to [Prod. Req. 1]

If, for example, the numbering of the 2nd requirement changes because a new "Cust Req" entry is added before that, this should also change the numbering of the corresponding "Prod Req" (product requirement).

Do I need a macro to implement this?

Any pointers would be helpful!

Thanks