Participants in the intervention group will receive six weekly 1.5-hour face-to-face NVC training sessions delivered by trained social workers.

The waitlist control group will not receive any training before all the assessments have been done by both groups. The wailist control group will receive NVC training sessions after all assessments. During the whole study period, these participants can access usual medical services, whether related or unrelated to mental health needs.

The intervention will be conducted by social workers who will be trained by professional NVC trainers through a train-the-trainer workshop, including six sessions. The interventions include an introduction to four fundamental principles of NVC, distinguishing observations from evaluations, identifying and expressing feelings, taking responsibility for feelings and needs, and using positive action language to make requests. Each session will feature a review of the previous session, a warm-up game and an exercise to consolidate the learning of the concepts. The intervention sessions will also include group discussions and debriefing sessions on parents' experiences of practising NVC.

The Short Warwick-Edinburgh Mental Well-being Scale (SWEMWS) is a 7-item scale for assessing mental health in non-clinical populations. Using a 5-point Likert scale (1 = none of the time, 5 = all the time), the total score is calculated by summing all seven items. The Chinese version showed good validity and reliability in the investigators' previous study. The congeneric reliability was 0.85 and the test-retest reliability was 0.70.

The measure of NVC skills was developed based on a 16-item scale that represents the four principles of NVC skills. Each item is rated on a 5-point scale ranging from 0 = never to 5 = always. The average score is calculated, with higher scores indicating better NVC skills. Cronbach's alpha was 0.82 in the investigators' pilot study.

The Parental Stress Scale (PSS) is an 18-item questionnaire that assesses feelings about parents' parenting role. A 16-item version of the PSS was developed by Leung et al. for Hong Kong parents. Responses are given on a 5-point scale. The Chinese version showed good internal consistency (Cronbach's alpha: 0.86).

Social workers' understanding of NVC will be assessed at TTT1-TTT3. Overall satisfaction with the workshops will be assessed during TTT2. Items are rated on a 5-point Likert scale (0 = strongly disagree to 5 = strongly agree).