This doesn’t seem to be an option in Elements (copied from the manual):
Copying and pasting notes into different voices
You can copy and paste notes into voices that are different to their original voices, including into slash voices. For example, you can copy notes from an up-stem voice on one staff into a down-stem voice on another staff.
In Write mode, select the notes you want to copy.
Press Ctrl/Cmd-C to copy the selected notes.
Select the staff to which you want to paste the notes, at the position where you want the selection to start.
Choose Edit > Paste Special > Paste Into Voice > [Existing or new voice]. You can also choose this option from the context menu.
The selected notes are copied to the selected staff and into the selected voice. …(NOPE)