Hi,

Based on my understanding, EventAggregator provides a Subscription Filtering feature which can come in handy in this type of situations. However, you will need to have a shared ID between your FilterViewModel and ResultViewModel so when you Publish the event, you send that ID as part of the parameter, and then the subscribers can filter the published events using that ID. There are different ways to do this, which mostly depends on how your application is designed:

• You can set a unique GUID when you initialize your SearchView and pass that GUID through injection to the Filter and Result view models, so they can Publish it and filter the events accordingly
  
• If you have another region inside your SearchView, which contains both your FilterViewModel and ResultViewModel, you can simply set a value to that region context and use it for your event filtering
  

If you need more information about subscription filtering, you can visit the following section of the Prism documentation:

• Chapter 9: Communicating Between Loosely Coupled Components - Subscription Filtering
  

Hope this helps,

Federico Martinez
http://blogs.southworks.net/fmartinez