亲爱的--先生和夫人你们好：不知这次上海之行是否开心呢?对上海的感觉如何?很抱歉没好好地陪你们.也许留些遗憾能想着再来上

Dear Mr and Mrs,
Hello.I hope you all had a wonderful time during your stay in Shanghai?What do you think of Shanghai?Sorry that I could not accompany you during you visit.Maybe,this will be the reason for your next visit.Thank you for giving the present to Mr.Segaram.We will talk again.Wish your family to be safe and happy.
regards,
(你的名字)