I'm not entirely sure from memory whether you can assign multiple keys or buttons to a particular ranges in order to have it trigger a certain range.
You cannot assign a key to a partial chain selection.
But this can be achieved using dummy clips which can be assigned separately to switch to these. (plenty of clips on youtube on how to do this.)
However, this is a better solution anyway since the chain selection can be synced to other clips that are playing. I never did find a video showing this. However, I did figure out that there is a chain selector automation envelope. So I created separate clips for each chain selection value.
Thanks for your help.