When two parts or more are selected, the slices can be unified to one single part. The original shapes will remain and can be separated again later.
In the submenu Extended in the context menu, there’s the option Merge Slices: The slices will become one slice file which includes all contours of the original. Overlapping contours will remain.
With
Clear grouping you can reverse this unification. And very importantly, editing operations you conduct with slices, such as merging slices, can also be undone by this function. Thereafter, the slice resulting from the operation is removed and a new group is created which will contain the original slices.