Can you help me fix a mixed drink?

Hi! While on a trip we came across a drink that consists of one part Grand Mariner (or triple sec) and one part peach schnapps. Then add a drop of bitters. This is ok, but the flavor is a bit strong. I think I am missing an ingredient. The original I had was less “boozy.” I would really like to figure out a way to economically make a pitcher of this for a party and some kind of filler would be good. Can you make a suggestion? Adding water just doesn’t seem right. Thanks!!