You may not need a child command. In the SQL section of the Command use a "join".
Code:
select * from orders inner join customers on orders.idno=customers.idno where datefield >= ? and datefield <= ?
Then at runtime
Code:
de1.Commands("Command1").Parameters("param1").value = somedate1
de1.Commands("Command1").Parameters("param2").value = somedate2
this is just an example, you will have to adjust it for your needs.