OK, let's say you have 5 rows in a block.
Insert a column on the left, and create a series 1,3,5,7 and 9. Then i
the cells below that, create a series 2,4,6 and 8 (insert blank row
first if you have to).
Then select the whole matrix and sort on the new column. The blank row
will end up between your original rows.
Regards
Mik