DFF on Requisitions Header

We're looking at adding some DFF fields but I'm wondering if it works like I think it does.  We're NOT placing then at the Global Data Element level.  We're adding 2 other levels below it.  We're using all 15 attributes for a new level we call Professional Services, then we want to use all 15 attributes in another level and call it Materials.  Then on the Requisition input form when I place data in the first set it's great.  But then when I select the Materials one and enter data there it blanks out all the data already entered in the