First, you need to move your blocks outside the group one by one (Sorry, but multiple sections isn't supported at the moment), Then you need to insert them into a Merge block.
You can warp all the relevant blocks with a Merge command using the Source tab by adding <Merge> and </Merge> before and after your blocks.
Moving the blocks outside the group have to be from the editor and not from the Source tab because the position of every block needs to be updated during this process.
Change the position of a "Merge" isn't supported, but you can ask this feature in here:
wantoo.io/cyberix3d
Regards,
Cyberix3D team