You can assign multiple surfaces to a selection set.
Before you begin: Open a 3D Shape containing two sets of neighboring surfaces,
and two touching curves running roughly along the intersection of the surface sets.
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Click OmniFillet
.
The selector panel opens.
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Click Side A and select the surfaces for the first set.
The surfaces are internally joined and assigned to the selection
set.
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Do the same for the second set (Side B).
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Click Spine and select the two curves.
The curves are joined as well.
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Click OK.
The fillet is created. Both the Omni Fillet Spine feature and the Join
features are added to the tree.