Embodied conversational agents (ECAs) are digital characters that behave like humans and utter humanlike dialogues. They are digital twins of a human coach and are cost effective and reachable as compared to human coaches who typically are costly and have long wait times for appointment. To support a healthy life-style, multiple health experts may be needed and our multi-agent digital twins give access to all the coaches in the same session. To provide motivation and encourage following the advice given, these coaches use relational cues in their dialogues including empowerment, working alliance and affirmation cues which are found in actual human-human coaching sessions. Our digital twins simulate three coaches who are experts in diet, physical activity and cognitive health which collaborate with each other, and the human, to provide a holistic coaching experience. This paper reports on our use of Generative AI to modify neutral dialogues with these relational cues. We recommend that both automated and human validation be undertaken in the context of health advice.