Piano Score - double parts

I am trying to create a create a piano part where I have 2 different things going on in the right hand, a semibreve tied over to the next bar with a melody (crotchets / quaver) below - how do I creat the 2 parts together in one bar. I know how to create chords but need different rhythms int he 2 parts so this method doesn't work.

TIA