While there are some apps that prevent grouping (a small minority and for reasons the devs could detail better), most should with standard Windows development practices. If you have an app already developed, and its not, can you provide more details?
If you have not, it would be prudent to finish said app and test when done.
Yes, is a legacy program made in delphi 7, maybe this is the reason for not working. I'm think about the compiler is old, i will try with the new delphi versions with same code and i come here to tell de result. But the question is answered, basically is related with the tecnology, right?