Reuben,

I am to be married, date to be determined, to Miss Helga Scamander. Please note that I have informed you well in advance, and indeed, have her father's consent and blessing.

Reuben,

[Awkward pleasantries]

Though not quite so exciting an addition as my charming niece, I am pleased to share that our family is to grow further still: I have asked Miss Helga Scamander to be my wife, and she has been kind enough to consent. I shall inform you of the nuptial details when there are details; in the meanwhile, I trust that you and your family will remain well. Though I should like to arrange some sort of formal introductions prior to the wedding, it will, of course, depend on what's to come.