Lord Darkstar
Grandmaster of the AFC
what sort of powers does Visas have?
if she is dark, then have her stand back and use force lightning on the sith, several of those and they should be badly wounded. While she is doing that, have Bao and the Handmaiden do melee attacks using shields and stims. After Visas runs out of force energy, then she can attack, by which time, all the sith should be dead
if Visas is light, then use all of the protective force powers, then go in and attack, liberally using force heal. Again, have shields and stims equipped.
if Visas uses both light and dark, then combine the two methods. Have her use force lightning, and heal.
Some more info on your situation (weapons eqipped, force powers, armor etc.) would be nice. But what I said above should work, good luck