i did not use
_BlendSrf. The first i did where splitting the edges at the 3 red arrows in my file. Then i created the 3 surfaces marked with an “A” using
_BlendSrf using Curvature option. While the
_BlendSrf preview was active, i´ve tweaked them using the handles provided to stay as close as possible to the existing geometry. Then every of the 3 blend surfaces marked with an “A” where matched on 3 sides using
_MatchSrf and the
_MultipleMatches option. In the
_MatchSrf dialog i´ve chosen Tangency, Match Edges by closest Points, Refine Match and Preserve Isocurve Direction. Next step was to create the 3 pipes, then Split the 3 Blends with them. This is to make room for the blends created in the next step.
I´ve created the 3 other blends to connect the 3 blend surfaces marked with “A”. These 3 where also matched to the short naked edge of the main part near the 3 red arrows. Finally the remaining hole was done with _Patch using the 3
_Blend curves to guide it (of course using Tangency). These 3 curves where created using the
_Edges option in the
Btw. after every
_BlendSrf command, i´ve selected the result and used
_RemoveMultiKnot. Most important is that you tweak the blend surfaces using the handles while it is created.