1) I am not sure to understand what you tell Pilou...

2) Yes, I trimmed instead of "booleanned" for cutting with an ellipse but after that trim I have closed the edges of the cut and now it is a "closed crv".
What do you mean by "some actions will be necessary" ? What I have to do ?

3) I understand the whole piece is not quiet to be filleted, that is all my question : how do it have to be ! ;-)

Thanks for your time !

Cordially,