Hi theres a shading issue on the upper chest of both the male and female shirts, make sure the edges of the neck are marked as sharp so that the shading is consistent across the transition. That could be the resolution.
Ive just taken a look at the model and the issue is still there.
i opened it in blender and i can see that there is a gap in the neck where the head meets the upper body. Make sure the verts of the neck line sit exactly on the position of the neck line verts of the neckline on the head of the base mesh model