user defined amount type

Hi

is it possible to create a user defined amount type in oracle applications 11.5.10.2. Instead of using YTD Actual could we call it XXXXYTD Actual and have a calculation XXXXYTD Actual Jul-09 equals YTD Jun-09 plus PTD Jul-09. The reason why I am asking is that due to a recent take over of part of our group of companys, two of the companys need to change their gl calendar from jan-dec to jul-jun. the other two companys will remain jan-dec. In June 09 we intend to do a year end roll. This will effect the companys reporting that have the