Cut angled beam into horizontal beam - how to?

At the handdrawn sketch you see what kind of cut I want to make in the horizontal beams.

How to do that? I have tried some cuts / connections, but it don't work out. The angled timber and the horizontal timbers belongs to two different walls.

Easy? The cut doesn't work out. What is 1st reference beam and 2nd reference beam? Should I use group or single?

Please hang on - because I have another connection I can't solve, I am not sure if the solution is the same.

Ok - I have to try again. Is it possible in D-cam to show only selected beams - and hide all other beams? I have so many beams, that my eyes are rolling...... :lol:

Oh - yes very useful icon - I didn't have them, so that's why I couldn't find them :lol: But now I've put them via settings.

But I did still not have succes with this cut. If I use single it says "cannot create half lap joint" and with group nothing happens.

Try and try until succes - as somebody said (I don't remember who).

Not much happens. I must be doing something wrong - or it is not possible.

I am asked for:

1) 1.st group of beams - I choose the two angled beams.
2) 2.nd group of beams - I choose the two horizontal beams.
3) 1.st reference beam - I choose the lower angled beam.
4) 2.nd reference beam - I choose the one horizontal beam.

Ok - here are the beams.

And here my settings.

Oooh thank you!!! It's perfect now. I feel like a balloon slipping the air...

:lol: Thank you very much for your help and time. Luckily I did not get crazy before we solved the problems....

:applause: :applause: