Loops And Building Comma Delimited Strings

The problem:

I have 2 tables, with a one to many relationship - lets say customers, and order items.

Each order record has a field that is meant to be a comma delimited list (they are reference numbers) that is driven by the quantity field. So, say in the order record, an item has a quantity of 3. The reference number will look like this:

1, 2, 3

And if the next order item for that customer has a quantity of 4, the reference number value is

4, 5, 6, 7

And the final item with quantity of 2:

8, 9

Reference numbers can either be auto assigned (and are in my web application) or manually set. If manually set they will NOT be numeric.

In my web application, it is possible for users to return to a customer's order and edit a line item. My problem is when users changes the quantity of an item, and I have to reset the reference numbers.

If the quantity of line item 2 changes from 4 to 3, I need to reset all the values for that, and any other, order item that comes after it:

4, 5, 6 (2nd)
7,8 (3rd with same quantity of 2).

I felt a cursor would be the best way to handle this. But I am having trouble re-assigning my variable to be the next number in the series when the cursor is running.

This is what I have so far. The print lines and hard coded values are for debugging purposes only.

DECLARE @NumberingType varchar(10)
DECLARE @TotalSum int
DECLARE @DoorLineItemID int
DECLARE @Quantity int
DECLARE @SeedInt int


SET @SeedInt = 1

SELECT @TotalSum = SUM(Quantity) FROM DoorLineItems WHERE UniversalOrderID = 12345

DECLARE UpdateRefCursor CURSOR FOR
SELECT DoorLineItemID, Quantity FROM DoorLineItems WHERE UniversalOrderID = 12345 AND NumberingType = 1

OPEN UpdateRefCursor

FETCH NEXT FROM UpdateRefCursor INTO @DoorLineItemID, @Quantity
DECLARE @RefNumberLine varchar(1024)
SET @RefNumberLine = ''

WHILE @@FETCH_STATUS = 0
BEGIN

WHILE @SeedInt <= @Quantity
BEGIN

SET @RefNumberLine = @RefNumberLine + CONVERT(varchar, @SeedInt, 101) + ', '
SET @SeedInt = @SeedInt + 1

END

PRINT @RefNumberLine

SET @SeedInt = @Quantity + @SeedInt
PRINT 'new seed: ' + CONVERT(varchar, @SeedInt, 101) + 'Quantity ' + CONVERT(varchar, @Quantity + @SeedInt, 101)


FETCH NEXT FROM UpdateRefCursor INTO @DoorLineItemID, @Quantity


END

CLOSE UpdateRefCursor
DEALLOCATE UpdateRefCursor


This returns the same delimited string for X number of items. So I'm getting this:

1,2,3
1,2,3
1,2,3


When I really want the results described above.

What am I doing wrong?

Thanks!