Can Stopping Zoloft And Haldol For Tourette's Cause Any Effects?

My 39 year old daughter is on Zoloft for OCD, Haldol for Tourette's and Lexapro. Is it possible we won't see as good an effect of Zoloft on her OCD as we would without the other two meds in the mix? She has been on Haldol for thirty years and I wander also if we got her off it; would perhaps the Lexapro control the tics in place of the Haldol? Thanks, Mary