Problem with sustained notes

I am writing a piece for piano in the time signature 3/4 and i want the right hand to play a chord on beat one of a measure and hold that chord for three beats ( dotted half notes). However, i want the right hand to play quarter notes on beats 2 and 3 while still holding the original chord. Every time I try and input a quarter note it changes the original chord to quarter notes or half notes without a dot. Does anyone know how to do this without having to tie chords together?