Standard usage in British English in the present day is to write initials alone, without full stops ('periods', for the Americans reading this) between them. It's usual to also omit spaces: Joe Devney > JD. Boris Johnson > BJ.

The last name change after marriage is considered 'other name' and you should create a 'multiple name affidavit' to prove both names belong to the same person. Some people add a middle name after marriage to add in-laws' last name to their full name.

This affidavit is required by a person whose names on the National ID are different from names on other certificates and title documents to correct the discrepancy. Certificates with different names from national ID.

Traditionally, a monogram reads First Name Initial, Last Name Initial, Middle Name or Maiden Name Initial. With the Last Name Initial being the larger Middle Initial. For example, if you had the name Kelsie Elizabeth Vogds, her monogram would read KVE.

An affidavit of one and the same person is also known as an affidavit of identity. It is a sworn statement that confirms that the different names found on different documents refer to one person.

Generally, you use the first letter of your first and the first letter of your last name as your initials, but you can also include the first letter of your middle name or maiden name, or more than one letter from one of the names (e.g. someone with the last name DiAmico using both D and A).

An Affidavit of One and the Same Person is a written document that establishes that various different names found on various IDs/documents refer to one person, the Affiant. This happens because of erroneous spelling of the name, a missing first or second name, or even an additional name or other names used, etc.