What is the Ah rating on your LiPo battery?
Also how do you want to control them? Via U2D2?
I just remember another Robotis recommendation which is not to daisy-chain more than 4 actuators within one mini-chain to minimize possible DXL control packet delays. So considering all that I would suggest 3 U2D2 power hubs because each hub has only THREE 4-pin connectors. So hub 1 for 9 dxls, hub 2 for 7 dxls and hub 3 for 8 dxls from the power point of view and have all 3 hubs share into a common ground with your controller (that is to hook up the power supplies in parallel). You also need to try to wire up the control circuit in parallel by using these 4-pin hubs - see picture below
