When attempting to resolve producibility problems with a given ply in Fibersim, you have many options outside of changing the basic surface geometry:
Assuming you have already ruled out 1 through 3, the question becomes: “How do I apply darting to this particular ply?” It turns out that Chapter 2 of the Fibersim user guide actually has a wealth of information on how to interpret producibility and apply darts based on the type of wrinkling encountered. It can be found with your Fibersim installation (%FIBERSIM_HOME%\FiberSIM\documentation) or by accessing the help menus via the UI. Some highlights:
Determining deformation type (Wrinkling vs. Bridging)
Remember, the dart type refers to its 3D shape, which actually has an inverse relationship to its 2D shape:
Effective Slit Dart depth
For V-Shape Darts, the best practice will depend on the design limitations you have. Since you are effectively removing an area of ply coverage, a patch will likely need to be created to fill it, which may necessitate enlarging the area to make the patch structurally viable. This makes it impossible to provide a generic guideline for effective sizing. Just make sure that the resultant flat pattern doesn’t overlap itself!