The "solution" only works if your "PARENT SPAN" has exactly zero or one "CHILD span" (i.e. just one date-span that is "inside it"; i.e. the parent span envelops just one...

Wow... I just wanted to post to say "I feel your pain" to the OP (david.edwards).  Sometimes we just have these absolutely ridiculous requirements that we can do little/nothing about.

Because this thread is such a high result on Google for "ssrs schedule last day of month", I wanted to link to this solution: https://dataqueen.unlimitedviz.com/2014/05/report-manager-subscription-last-day-of-month/ .  Essentially, while SSRS scheduler...

It sounds like he's talking about in a SELECT query.  Unfortunately, the answer remains the same -- you can't have the 7th column output of your query depend on the...

Wow, SO many things going on here...

And I don't mean to be blunt, but please, PLEASE go read the following articles:
http://sqlperformance.com/2014/06/t-sql-queries/dirty-secrets-of-the-case-expression
http://sqlblog.com/blogs/aaron_bertrand/archive/2009/10/16/bad-habits-to-kick-mishandling-date-range-queries.aspx