double stem on 1/2 & 1/8 notes

I'm using two voices in a score and would like to be able to have a double stem on a shared 1/2 & 1/8 note and keep it hollow (to show the 1/2 note). MuseScore automatically places them side-by-side because one is hollow and the other solid. If I manually move them together, then the solid 1/8 note fills in the hollow 1/2 note. Is there any way to keep it hollow?

I've attached an image of what I'd like to be able to do.

Thanks for your help!