Hi Lara,

this is my new try. As you can see I copied / pasted the edges so that I have 3 red curves.
I then created a circle profile (green) and sweeped the circle along each red curve. Once
I had the 3 pipes I boolean subtracted them from the main surface. After that one only
needs to blend the edges. The remaining open triangular hole was networked.

Hope this helps!



Regards
Stefan