How can i join vertex of the same bezier? I have to complete a 3d job and I think that for this piece it is best to use bezier or curves. I am a little novice with these tools and I can't find a way to draw "a bridge" between some vertices.  

I tried with the F key but it does not let me connect them and it is not enough just to join 2 but it would have to be 4: (with the photos I hope that I understand better). 

The piece is somewhat complex and I only manage to do it on the one side. My idea is to avoid  polygonal modeling as much as possible.
You can only make a cyclic curve, there is no way to join it multiple times as far as I know.