I had a look at your file: The problem with moving support is easily fixed. We use springs for the supports and you have to apply higher spring stiffness. This can be adapted by right-clicking on the AnalysisModel and setting the penalty factor to a higher value (I added two zeros). This improves the coupling between the patches as well. Then simply update this component by newly connecting a wire upstream.
Regarding the forces, this is also related to the supports. Since you are using point supports, the support is only added to one patch where then high force concentration occurs. Line supports of small lengths are typically better for shell analysis without edge enforcement (as in classical FEM) if the region of the support is important in detail.