"Create Group" at Sub-Group Level Security

we are currently using BO 4.0 SP4 and am wondering is it possible to have a user group with a permission to create groups only at sub level and not at top level?

eg:  Top Level folder

               Group 1

               Group 2

               secGroup1

I have secGroup1 group which will have full control on "group1" group but will not have create group options at top level above "group1" group level. is it possible in BO 4.0? I am currently testing and it seems it is full or nothing (you should give create group at top level or no create group at all)

that would be an important security piece and am sure BO would have it some way

thanks

Kenny