Analysis :: How To Pass Apply SSRS Parameters On Multiple Dimension Attributes

How @StartDate and @EndDate parameters must added to the MDX query for usage in SSRS data set. strtomember can be used like

SELECT (
strtomember(@StartDate) : strtomember(@EndDate)
) ON COLUMNS FROM [Cube]

How can i specify that sub-select must work on the [Fact A] and [Fact B] rundate? strtomember(@StartDate) does not specify on which attribute this sub select is going to work. Any pointers ?

FROM
(
SELECT
(
[Fact B].[Rundate].&[2015-01-02T00:00:00] : [Fact B].[Rundate].&[2015-01-15T00:00:00]
) ON COLUMNS FROM
(
SELECT
( [Fact A].[Rundate].&[2015-01-02T00:00:00] : [Fact B].[Rundate].&[2015-01-15T00:00:00] ) ON COLUMNS FROM [Cube]
)
)