Children and adolescents with intellectual and developmental disabilities (IDD) are more likely to engage in challenging and interfering behavior than their typically developing peers, which has been linked to many negative outcomes. The most effective interventions to address challenging and interfering behavior incorporate function-based assessments, which are used to develop individualized behavior interventions. Functional communication training (FCT) is an evidence-based practice to decrease challenging and interfering behavior that can be taught to parents using behavioral parent training (BPT); however, there are limited skilled professionals who can develop interventions and train parents. Telehealth can enable greater access to these professionals. This study used withdrawal designs to determine whether high parent treatment fidelity resulted in decreased challenging and interfering behavior and increased appropriate replacement behavior. Three participants (8-17 years) were included in the study, and their parents served as interventionists during mealtime, toothbrushing, and room cleaning. Data were analyzed using visual analysis. Each parent achieved high treatment fidelity with one session of BPT and bug-in-ear coaching. All participants had a decrease in challenging and interfering behavior and an increase in functional communication responses (FCRs) upon the introduction of the intervention with reliable reversals. All parents reported high social validity. Results and implications for practice and future research are discussed.