In two films about the Titanic, Murdoch was portrayed shooting passengers and himself during the sinking; this was based on a number of eyewitness testimonies of a shooting/suicide by an officer during the launching of the last lifeboat. It is possible that Murdoch was the officer.
In general, to append is to join or add on to the end of something. For example, an appendix is a section appended (added to the end) of a document. In computer programming, append is the name of a procedure for concatenating (linked) lists or arrays in some high-level programming languages.
An addendum is something that is added and made part of the original document only if it has been accepted by the concerned authorities. An Addendum is an informational or explanatory note of the requirements of the parties concerned that have not been specified in the original document.