Doubt in BPM

Hi,

Assuming that I am implementing BPM, i have following doubt:

Suppose I receive different PO data from 3 different vendors. Say Vendor1, Vendor2 and Vendor3.

Assume that I get PO from an Vendor3, who sends individual line items instead of sending full PO with line items.

And in this case, I choose to implement Collector Pattern in BPM.

My doubt is how do I put a condition such that '<b> If I receive from Vendor 3 only, I need to implement Collector pattern'</b>. How do I put these conditions to check for the right vendor in BPM?

If any one has any suggestions, please clear my doubt.

Thanks