BI review & help

I'll start from the bottom line: If you create your Data Warehouse and you follow the DW rules, you're life will be easy (assuming you know the semantics and the way to build a good and correct DW).
In our case, if you have a dimension and you want to make a Parent-Child hierarchy, your life will be easy if you built the dimension's table in the right way.

For example, let's look at a simple Time dimension:

Time_Key	Day	Month	Quarter	Year	Level_Num
01012008	01	01	1	2008	1
30122008	30	12	4	2008	1
01/2008		01	1	2008	2
12/2008		12	4	2008	2
Q1/2008			1	2008	3
Q4/2008			4	2008	3
2008				2008	4

As you can see, this time dimension's table contains the days 01/01/2008 and 30/12/2008 and their parents in the levels: month, quarter and year.
Now, let's say that I need to take this dimension and make it a Parent-Child table. This is very simple. Just create a view with one new column which will be the parent column. This is the new column's code (in Pseudo-SQL):
if (level_num = 1) then Month + "/" + Year
else if (level_num = 2) then "Q" + Quarter + "/" + Year
else if (level_num = 3) then Year
else null

The result:

Time_Key	Day	Month	Quarter	Year	Level_Num	Parent
01012008	01	01	1	2008	1	01
30122008	30	12	4	2008	1	30
01/2008		01	1	2008	2	1
12/2008		12	4	2008	2	4
Q1/2008			1	2008	3	2008
Q4/2008			4	2008	3	2008
2008				2008	4	null

This is it. Now, in your OLAP DB, just configure the new column as the parent and you have a Parent-Child hierarchy. In Analysis Services you even don't have to create a view. In the Data Source View you can add a named calculation and put your code there.

See? When you create your DW according to its rules, the life is easier. In this example, if you created rows for every level in the hierarchy and created a descriptive key - everything is great.
This can help you in many scenarios. For example, when you find that your dimension is not balanced then you might want to make it a parent-child, so you won't have many pseudo-levels when the only relevant member is the leaf. Otherwise, this can be very annoying to your user. In SSAS, make sure you don't use it too much, because it is bad for performance.