Dear [DCB],
I hope you are healthy and happy when you receive this letter. I apologise for not getting in touch with you earlier, but recent events have forced me to do so in order to ask for your advice and support.
My parents are having a disagreement right now, and I think your knowledge and experience could help us get through this difficult circumstance. I'm hoping you can offer your insightful counsel and assistance as an uncle who has always been a rock of support and understanding. My parents' arguments have become more and more heated over the past few weeks to the point that it is compromising the stability of our family.
I humbly request that we set up routine video calls or any other type of communication so that you can help us get through this challenging time. I have faith in your judgement and am confident that any course of action you advise would be in our family's best interests. Your advice will add to our long-term harmony and happiness as well as to resolving the current conflict. I appreciate you taking my request into consideration, Uncle. I eagerly anticipate your response and pray that you will be able to give us the support we require during this trying time. Please give Aunt [Aunt's Name] and the rest of the family my deepest regards.
With sincere gratitude,
(ABC)