if you get the backing chords for the 1st song, a sax accompanyment melody/solo should be quite easy to figure out.
the 2nd song i would be more inclined to play harmony on the sax – a lot more difficult.
interesting to see what you come up with.
The last school concert i went to, 2 lads got on stage, one played keyboard & the other lad sang.
When i got home, my eldest daughter told me my youngest daughter wrote the harmony for the music! Apparently no one in here year could write the harmony, they were all stuck on what to write, so she discovered she’s got a natural ability for figuring out/writing harmony! (pleased as punch i was)