Question about filtering on NOP formula result

Hello,

I have a question about filtering on availability on a property 'pushed' via NOP formula. I have a report table that is showing for a given array the list of all LUNs and the datastore associated with the LUN (in our env 1 LUN = 1 DS), and as sub report for each Datastore the VM's that are using it. The structure looks like that:

• Main report  Expansion on device with filter devtype=='Array'
  • Expansion on part with filter parttype=='LUN'     +  NOP formula to push up the datastore name (DSName)
    • Complex expansion on "partsn join on partsn" to create the link between the LUN and the DS   + NOP formula to push up the datastore name (DSNAME)
      • expansion on device with filter devtype=='Datastore'    + NOP formula with empty parameter and device property attached to it (Result name of formula : DSName)
        • Complex expansion towards VMs linked to the datastore
          • ...

In the Main report I have the following columns:

Name: Arrays SID              property= 'device'

Name: LUN                        property= 'part'

Name: Datastore name     property='device' with Selected Value= 'DSName'

This is working fine we have the match between the LUNs and the datastores. But the problem is as we do an expansion on LUN we have all of them even the ones where there is no datastore attached.

How could I do a filter to say "Show me only the LUN's where the property device of the formula result DSName is not empty" ?

Thanks,

Jean-Michel