What are you trying to do? I really don't understand what you are asking? Current load calculations are just adding up the loads in kW or kVA and then converting to current. No problem there. Not clear on what you mean by balancing.
Add them up on a phase-by-phase basis. Total load in kW or kVA (use the same for all loads) and evenly divide the load by the number of phases connected. Sum the three phases, see how well it balances, move loads as necessary for better balance.
You should also balance the line-to-line loads as well as possible separately from the line-to-neutral loads. This is because of the phase angle difference between line-to-line and line-to-neutral loads.
