You have to think about the direction light when you bounce.
Rebound is not just about pointing the flash up, or up and down. It is a question of choosing The direction from your light. If you bounce, you must stop thinking about the flash as your source of light, and think of the reflective surface your flash is pointed as a light source. In other words, aim the flash head toward where you want to place a softbox in the studio. In this case, you place the light on the ceiling, directly above your head, more or less downward.
If you want the light to come from further ahead, you have to bounce behind you. But there may be no reflective surface (wall) at this location. So, choose where you do this, and how the room is shaped / how far away are the walls / ceiling are all key elements. The higher the ceiling, the less you'll be able to bounce back, because light, like all forms of electromagnetic energy, fades in a reverse square. (1 time2). Double the distance, you quarter the light; triple, and you are at a ninth. There is reason to continue using a high ISO setting, even if you are using a flash.
You may need to install a reflector or reflective surface, or rearrange the location of the group so you can use a reflective surface. Or. Consider turning off the camera's flash and triggering it remotely (most often with a radio transmitter / receiver).
See also: Neil van Nierkerk's website, Tangents. It has a ton of information on the rebound of a flash on the camera.