Mosiqaar,
What you can do is create/edit 2 similar programs, Program1 (string sound starts at where your split point is) and program2 (string sounds goes as far as C1). The only difference will be in the range of the keys you assign under program edit 3/3. This way, when using the LHS with the autoaccomp, you can use program1; when in pianist mode, you can use program2.
Hope this helps,
Thanks,
AJ