I do this type of thing a lot, but having it be concise and easy is not usually possible.
I did like the challenge though.
It did become a lot neater and easier, with less components if I eliminated combination 4, the parallel 4AA/2=3V.
If you can live without that, the below circuit should work.
I'd rather not go into detail about why #4 wont work easily, but i can PM you the other diagrams i have where i diagrammed the problem.
Hope this helps!
aka The Other David
Switch is a rotary 2-pole/5 or 6 position.
Now, if you wanted to add a separate switch to engage the #4 function, that *can* be done.
"In Theory, the is no difference between practice and theory. In Practice, there is."