Your c/line doesnt look perp to the off vertical line anyway ?

You should convert your Int.spline to a CPspline and it might become more apparent what is needed, that is if I understood you correctly:p

Are you trying to lose the dip in your curve whilst mainting some kind of symmetry to the line....it's sometimes better to post the geomtry you are working on along with some notes in the file ?

Ohhhh just thought...Is there a way to place typo notes in these files - Tim ?

OK - here's one way....

If you are trying to lose the dip follow plan B otherwise here is one way that will lose the crease if you surfaced the curves.

Personally I would work with CP splines....much more forgiving and editable, convert them and turn on points.

Draw a line perp from the endpoint of the vertical line (horizontal line). Open the spline palette and use modify slope by reference using the line this should now be perp to the vertical line ?? If that's not your thing...move on;)

Plan B

Create another horizontal line that is longer than the first three cv's on that curve. You are now trying to align those three points along that line OR construction line, you can drag the points to "on" the line. I rotated them (3pts) using the first point as centre then the curve point followed by anywhere on that line...this will flatten the curve perfectly.

Make sure you show best resolution and even distrobution to show the effect

HTH