Is there a command to merge two points into one point?

I don't believe that is existing...
It's not Points of segments, it's "Control Points"
So just move your curve(s) by its extremity(ies) anywhere you want...in your case on the other extremity...
or for example in the middle of them with the Help oh Helpers lines...if that is wanted...



For see "helper line" Click and move without release, release...
After the call of a function, before the first Click of the function, after the first click of a function, before the last click of a function...

Some options are possible (Relocate, Reoriente etc) if you click (Left or Right) the little "White Tab" of the "Helper Line" after a Move click... :)

Hi feirui445, yes like Pilou says there isn't a specific command for that but you can get it done using the Transform > Move command using a construction line to find the midpoint between them for the first move.

Usually NURBS modeling is at its best when you are generating your model from mostly 2D profile curves, rather than directly placing surface control points. So surface control point editing is not a major focus area in MoI's toolset like it would be in a polygon modeler.

- Michael

Hi feirui445, there are some previous examples here about how to approach things by making extended shapes that are booleaned rather than building things in a "fill in a 3D wireframe patch by patch" type manner, they might be applicable:

http://moi3d.com/forum/index.php?webtag=MOI&msg=10210.16
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael

Thank you. The tutorial on the forum is a good inspiration