Filter Child back to Parent(s) without using bidirectional?

[OneWithQuestion]

What is the "easiest" way to enable filtering on the child record so that selecting a child record will filter the parent(s)?

In this scenario, not all parent records have children.  

I have a mockup with Customer and Payment Method, I'd like to be able to click on a child Payment Method and see all the Customers (parents) who used that payment method.

I can filter parent to child of course (selecting Jane shows Cash, Credit, Debit)

But, what about selecting "Credit" so I can see everyone who used that?

I could add a count of Payment Methods to the Customer data grid, but I have to instruct it to show items with no data or it will hide all the parents without children.  If I show items without data it won't filter either, it will just show counts.

*Granted, in the real world you should not have customers who have no payment method, this is just a mockup example.  

[bcdobbs · Accepted solution]

Just realised your need to show parents without children. Will see if I can modify.

[bcdobbs]

If you create a measure like

ParentFilter = INT ( NOT ( ISEMPTY ( 'Customer Payment Methods' ) ) )

and put it on the visual level filter of a parent visual (or slicer) with it set to "Is 1" you should get the desired interaction.

[bcdobbs · Accepted solution]

Just realised your need to show parents without children. Will see if I can modify.

[bcdobbs · Accepted solution]

Think this works:

PaymentMethodFilter = 
IF (ISFILTERED ( PaymentMethod ),
    INT ( NOT ( ISEMPTY ( PaymentMethod ) ) ),
    1
)