Two-staff arpeggios suggestion

Please, could you add arpeggios in two staves?

I mean, that if I put an arpeggio to top staff, and extend it to the staff below it, it will play only the top staff as arpeggio, and vice versa. This should be fixed. It could be useful for music that use harp.

If I put arpeggios to both staves, it plays both staves at the same time, and this is what I don't want.