Editing existing Faces with a Spline and Swept Surface while maintaining part features.

Hello all.  Newbie here. I have wasted all afternoon on this.  I cannot afford to rebuild the part from scratch.  I need to create a "flare" effect on this part.  The first photo shows the current model, the second shows a real world model of what I am trying to accomplish, and the third shows my wasted time.  The current part was extruded from the Mid Plane if that helps.  I achieved the look I did in the last photo using a Spline and Swept Surface, but it is not actually part of the original part as you can see.  How can I edit the current part while keeping all the other features and dimensions intact?  The path for the Sweep would have a 200mm x 92mm rectangular footprint.  I cannot lose the position of the hole and notched area on the top or the two posts inside. The width and length at the top of the part is fixed as well.


SolidworksParts And Features