The simultaneous control is an incremental technique which can be applied to shape analyses with soap film elements, when the shape has so large volume and high rise. Furthermore, the tangent stiffness method is a clear and strict analytical theory to be able to solve the problems with large deformational behavior. The simultaneous control brings out the best performance for form-finding of isotonic surfaces in combination with the tangent stiffness method. This study proposes a significant modification of the simultaneous control. The modification realizes a wide application range about load conditions and boundary conditions for soap film shape analyses by calculating the average of surface tensile. Results are presented as some computational examples in which the behavior of soap film structures under air pressure and /or water pressure becomes evident.