Help with relationships

Hey,

I guess you are looking for a measure like this:

Measure = 
CALCULATE(
    SUM('Invoice'[[Invoice]] Amount])
    , CROSSFILTER('Job List'[[Job]] Job No.] , 'Time'[[Job]] Job No.] , Both)
)

Using CROSSFILTER allows to avoid many-to-many relationships, but still provides the possibility to use the filter direction "Both".
This allows to create something like this:

But, I'm not sure how you want to treat the fact, that Brenton and Chris have worked on job number "1901-0001" and for this reason the measure shows the same value. But this is not an issue of the measure, but this is due to data distribution. Of course this can be used to calculate some kind of "share".

Hopefully this is what you are looking.

Regards,

Tom