Static simulation of assembly that is in a strained state at start

What license for simulate do you have? Creo Simulate Lite/Standard/Advanced or Simulate Live? Or do you mean you have Creo integrated ANSYS option?

For leaf springs like this the modelling technique depends on what loading or analysis scenario you are investigating.  For example lets consider a truck bed with leaf springs. The leaf springs start out separated except at the ends. When gravity is applied and a load in the bed, the springs deform to contact more and more along their length. This could be modelled with contact conditions along the springs. However if you wanted to then check the natural frequency in the loaded state a different approach is needed. This is because modal analysis is a linear one so contacts are not allowed. In this case you need the geometry of the springs in the deflected state, close enough so you can make coincident surfaces where the contacts would be and then make a bonded connection. For example you could first do the loaded bed with contact study, then export the deflected spring shapes then reverse engineer the shape in a new CAD model and define the bonded faces. For verification you would want to check the stiffness - (slope of force deflection) for this bonded model in comparison to the one with contacts to confirm the same stiffness has been modelled. Like you suggest other FEA software can tie together parts over a gap easier. That can also cause issues however because often there is not enough scrutiny about where in the model things get joined. Even if you export to FEM and use this technique you will face the question about how far along the spring to tie them together. If you let us know about what simulation license you have and any other details on loading or screenshots you feel you can share, the community will have some better ideas for you and help you confirm whether an external solver is needed.