you can override the playback of the grace notes and the big note after them, dragging the notes in the Played Duration view of the Key Eitor, to the desired position (you can set the grid in the key editor tool-bar to 32nd value for better positioning/orientation):
Beside my previous suggestion (which may be useful for other cases), a more elegant way is to set a high value for the Playback start offset on the big note after the grace notes . The grace notes will magically follow, as you increase the value. Tip: open a new windows to visualise both the properties panel and the key editor (in Played Durations view) side by side, to see the changes as you increase the value :