Hello C@Dors
Sometimes I need to connect the midpoints of 2 entities, except that if I can select the 1st, selecting a second one is impossible for me.
I select the first point with a right click on the line, then " select midpoint ", but impossible to grab another one since a right click on another entity deselects the first selection... 
So is it even possible to have 2 or more midpoints in the same selection?
Hello @Sylk ,
1 - Right click + Midpoint selection on the bow
2 - Holds CTRL + Segment Selection
3 - Choose midpoint relationship
And presto:
Have a nice day...
Hello @a.eriaud thank you for the answer, but...
In fact, it would be more to have a relationship such as " vertical " or " horizontal ", as you can do with the endpoints of two different lines.
The goal is to be able to align the center of 2 lines without having to add construction lines or other joy.
In concrete terms, this would mean doing:
except that it's not feasible...
It seems more complicated but...
If you draw your 2 segments with a midpoint line:
SW puts you directly a real point in the middle that you can then select.
So no addition of stitches or construction lines in a second step.
Sometimes, you just have to change your drawing method a little to make your life easier...
That's what I was going to advise you too: create your middle points and then align them with " vertical "
Your basic idea seems to me a bit " unstable " for solidworks
