Yes, it is possible to sort the groups in DataDynamic Reporter, but taking into account this basic rule.
The way groups are displayed depends on the order of appearence of the first variable of the group in the 'original' variable list.
So let's say your datafile contains the following variables in the following order:
If I create 1 group called 'group1' with variables E1 and A2 and
another group called 'group2' with variables B1 and C1
then group2 will be displayed on top of group1. But what if I would like to have group1 on top of group2?
In order to have group1 displayed first, you need to change the sorting of the original variables, in this specific example just put E1 somewhere before B1.
NB: don't forget to save the file after changing the order, otherwise changes will be lost.