Hi BurrMan,

>>The inset tab creation from there?<<

The inset tab was made from a Network.

I created a circle from the original model. The red lines where part of the construction and left for later use.



I trimmed off the top of the circle, then used blend to blend each side of the circle and the center line to lines placed at the top of the cutout.



I then added 2 3_point_arcs (yellow curves) to help with the Network




I then joined/added trim points to create the Network, I also used the top edge of the cutout as part of the Network for the blend.

I have colored the curves to show the network:-