Joining 2 Surfaces (for CNC)

Hi all,
What would be the best way to join this 2 surfaces? (file attached) I’m trying with many different methods, but don’t know which one would be the best.

Please take into consideration that this piece will be CNC’d in the future to produce a mold, so any comments will be much appreciated in terms of manufacturing quality.

Many thanks.

Joining_Srf.3dm (4.0 MB)

Untrim the hole in the wing surface as well as the blend surface. Curve dup edge of the blend and back surface. Use curve pull back Loose on the wing surface. Trim then surface match the blend surface positional match closest points/refine match preserve isocurve direction.