How to deal with 0...n or 1...n mappings?

Hi all,

I'm relatively new to BPM. I've already made several processes that are working fine. However, I'm now stuck because, for the life of me, I'm not able to understand how to deal with data mappings of nodes of a cardinality greater than 1...1.

I'm used to dealing with 0...n inputs of Web Services in Webdynpro Java and CAF Application services, using java code... but I just don't get how to deal with these in a BPM data mapping scenario.

Let's say you have a Web Service whose input is a node called "Employee", where you can add n Employee objects, like this:

   Employee (0...n)      FirstName: String      LastName: String

How do you:

1- map a 0...n context node from a Web Dynpro or Web Service output, already containing several employees, into this Employee 0...n WS input node?

2- map a 0...n context node from a Web Dynpro or Web Service output, containing NO employees, into this Employee 0...n WS input node, without getting an error and the BPM crashing because it says the employee element is not found?

Hopefully someone can help me with this, because I'm about to go the way of calling the web service n times, one employee at a time, instead of one time with a Employee object with n registries in it.

Thanks!