How to remove points on a 3D spline resulting from a feature conversion

Hello

I want to make a smoothed surface or boundary and one of the profiles is a 3D spline resulting from a conversion of entities (of an imported object in addition to ... )

The problem is that this object has non-symmetrical areas in its surfaces and so the resulting 3D spline, although symmetrical, has points on one side and not on the other and yet the curves on each side of these points are tangent, so in the end if I could remove them, it wouldn't change anything about the profile of the spline


So I tried to remove this kind of "parasitic" point but no possibility then otherwise to add an additional point on the other side but as it is a curve resulting from an entity conversion it is not a spline and therefore no possibility to add a spline point...

On my sketch you can see a relatively well "connected" ellipse but if you look at it more closely it's not the case: the mesh lines are not symmetrical... And if I put a more complex shape than an ellipse then it's the berezina!

Of course, there are green dots that allow you to "align" the mesh, but in this case with more complex profiles, they don't want to align with the plane of symmetry, as shown in my other example


What to do?
Thanks in advance


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