My sister and her fiancé have decided to exchanging marriage vows and I have been assigned the duty of inviting people who have been close to us.
You have been a family friend for a long time and you are one of those who are on top of the invitation list. I have sent this invitation so that you can have ample time to prepare for the occasion. I know you are a busy man and attend the marriage will affect your schedule, but I hope you can find time to celebrate with us in the special event. I have enclosed the details of the ceremony for your guidance.
Should there be anything that will hinder you from attending my sister’s marriage, we perfectly understand. But I hope you can let us know in advance so we can adjust accordingly.