triple apogiatura or grupeto in double strings

Dear Sirs In a song we are editing, it has a triple apogiatura, or a grupeto with two overlapping notes, that is, in double strings. I do not know Musescore program resources to do this, you have an orientation on how to do it ?. To facilitate the understanding I will send an attachment of a piece of music where the second staff, in the first bar has this apogiatura or grupeto