Excel: How to treat multiple lines as one while sorting?

I get a XLS-File as a database report. The File is in the following format:

   | Customer | Name | ... | Orders
 1 |     6    | ...  | ... | 1234
 2 |          |      |     | 4567
 3 |          |      |     | 8910
 4 |     3    | ...  | ... | 3210
 5 |          |      |     | 8765
 6 |     1    | ...  | ... | 1000
 7 |          |      |     | 1001

I need to sort this thing on a column which is only "filled" in the first line of a "record" (here: Line 1-3, 4+5, 6+7) like "Customer" in this example. Is there a way (without falling back to VBA) to keep the lines together which form a "record" while sorting on them. I know, this is abusing Excel but I have no other choise here.

The expected output after sorting on "Customer" would be:

   | Customer | Name | ... | Orders
 1 |     1    | ...  | ... | 1000
 2 |          |      |     | 1001
 3 |     3    | ...  | ... | 3210
 4 |          |      |     | 8765
 5 |     6    | ...  | ... | 1234
 6 |          |      |     | 4567
 7 |          |      |     | 8910

You could create an additional column that fills in the blank and use it for sorting purposes - assuming customer is in column A and the new column in column E, you can put in E2:

=IF(A2="",E1,A2)

and drag the formula down.

Every time you change the data, you would need to make sure the formula is copied to the bottom of the range containing data.