I think that this technique (using AdventureWorks as an example) does what you are looking for. You should be able to adapt it to your needs (providing you have a level above store in your hierarchy):

WITH MEMBER SPCount AS

[Geography].[Geography].CURRENTMEMBER.PARENT.CHILDREN.COUNT

SELECT

{[Measures].[Reseller Sales Amount]} ON 0,

NON EMPTY

GENERATE (

[Sales Territory].[Sales Territory].[Country].MEMBERS,

[Sales Territory].[Sales Territory].CURRENTMEMBER

*

TOPCOUNT(

FILTER([Geography].[State-Province].[State-Province].MEMBERS, [SPCount] > 1),

1,

[Measures].[Reseller Sales Amount]

)

)

ON 1

FROM [Adventure Works]

So in the example above, it excludes a sales territory (United Kingdom) as it only has 1 "State-Province" (England).

It's a bit of a fudge but frankly, I don't care 😛