If you are playing two songs in F, the target key, for both of these songs will put you in the key signature of D for both songs.
When we say that an instrument is a Bb or Eb instrument, what we mean is that when the Bb instrument plays a Bb and an Eb instrument plays an Eb, in reality they are sounding a Concert C.
Your Eb alto is a minor third above the Concert C. So to get to the Concert Key you have to write is a minor third down to match the concert Key.
Such as
C=A
Bb=G
A=F#
Ab=F
G=E
Gb/F#=Eb/D#
F=D
E=C#
Eb=C
D=B
Db/C#=Bb/A#
That is if you are just playing off the sheet in the Key it is written.
However, neither of these song are written in F. This first song is one step above a concert F ( in Concert G) and the second song is a half step below the Concert F in Concert E.
If they were playing "I Was Made To Praise You," in G, the Key it is written, then you would just play it in E. But since they are playing it in F. You need to go from G to D, since they are playing it in F, you need to transpose from G to D, which is a fourth down. D being your target key.
G=D: Gb/A#=C#/Db: F=C: etc.
If they were playing "I Just Want To Praise You," in the key it was written, you would be in the Key of C#. But they are not, they are going up a half a step. Again, if the group is playing in F, you need to play in D. But the music is written in E. Then we go from E to D, which is down a full step, so that you are a reading a minor third below the key they are playing in..
E=D: Eb or D#= Db/C#; D=C: C#/Db=B:, etc.
Whenever they play in the Key of F, you play in the Key of D. This is why they are going a full step down (first song) and a half of step up in the second and you are going a fourth down in the first song and a full step down in the second, to keep a minor third below them. They are going to F and you are going to D.
If you are using a chart and have chords, just lower the note as indicated above and keep the chord structure the same. (maj7, sus, min7, etc.)
The first is in the Key of G but will be played and sung in Key of F (both songs will be played and sung in F). I have transposed this to Eb without any problem.
If you have transposed it down to Eb, you need to go down another half-step to D, since they are playing in F.
It's a lot work, and they don't understand. Write it out beforehand if you have the music with you. After all is said and done, they wind up with one flat and you wind up with two sharps. Not a bad deal.
This would confuse most mortal musicians, but then we are saxophone players. The more you do it, the easier it gets.
Peace,
Chris.