How to get Current Member of a set of Children

[Sandy10]

Hi - I'm working with TM1.  I have a hierarchy, [PricingAnalysis].[P_RelationshipType].[P_RelationshipType].  It has 1 member called [All Relationships] that has children.

In a crosstab, I'm putting year/month along the columns, and I pulled in [All Relationships] on the row.  I'm using the following calc to conditionally format the facts cells, and it works.
I pulled in children([All Relationships]) under [All Relationships], and I can't get a calc to work.  the currentMember of  [PricingAnalysis].[P_RelationshipType].[P_RelationshipType] is always [All Relationships].  I need the current member of the set children([All Relationships])
so this calc will work for the children of the member.  Can I do this somehow ??
Thanks  !!!!!

value ( tuple([Sales_USD$/MONTH day],
                 [currentMember([PricingAnalysis].[Time].[Time]),
                 [All Relationships], [SOUTHEAST REGION], [All Products]) )  -

value ( tuple([Sales_USD$/MONTH day],
               PrevMember(currentMember([PricingAnalysis].[Time].[Time])),
   [All Relationships], [SOUTHEAST REGION], [All Products]) )