Joining Beams on different staffs

I am working with piano music. I would like to know how to join beams (and notes) when the notes are on both treble and bass staffs.
It is a tuplet with relationship 19/16. It begins on the treble clef, and the last note in that clef is A (below middle C). It continues to G→G→C (descending) in the bass clef. I have had to give them separate beams, but want the whole tuplet to be given one beam.

Thank you