If you need to use slicepicker instead of slicetree and you want to introduce hierarchical choices, you have the possibility of using {sliceHierarchy: } with the options : "none" | "filter" | "ask" | "clear"

The hierarchy style code impacts the next slicer
none : for full unconstrained choices
filter : removes non existant choices based on the current constraint in the slicer
ask : automatically fills the slicer to the only possible choice (if there's only one choice), otherwise clears the slicer
clear : always clear the slicer if there are no existing choices

Hover on the stylecode in the IDE for the full explanation