MoI does not yet have an easy way to edit surfaces later on to smooth them with one another.

You can still get smooth results, but you have to make sure that your curves are set up before your sweep so that they produce results that don't have a crease.

Usualy this means carefully placing the second control point inside from the end of the curve, which controls the tangent direction at the end of the curve.

Also, sometimes it is easier to get a smooth result by setting up the sweep using a full curve (mirror and join the profiles first) for all the profiles instead of doing it in pieces, then your result is generated all in one shot instead of mirroring it.

If you would like to post the curves here, I could show you how you would tweak them to produce smoother results.

- Michael