The two kinds of claim in a memoir
A memoir contains external facts and private recollection, and only one of the two can be verified by anyone. The distinction decides what an editor is able to do with each.
External facts are dates, places, public events, song titles, job titles, the make of a car, and the weather on a particular afternoon. They can be checked against a reference work, and errors in them are the kind a reader notices. Verification of that sort is copy editing as Editors Canada defines it, which covers editing to ensure correctness, accuracy, consistency, and completeness, including checking factual accuracy.2
Private recollection cannot be verified by an editor, a publisher's lawyer, or the author. What a room felt like, what someone meant, and what was said between two people thirty years ago are not checkable propositions. The honest editorial handling is to make the text say plainly that it is recollection, rather than to present it in the same register as the checkable half.
A novel contains neither category in that form. Its facts are invented, and the warranty attaches to whatever it takes from the world: a real person, a quoted lyric, a described place. That is a much smaller surface, and it is checked by inventory rather than by verification.
What an editor can actually do about the warranty
There are three, and each of them produces a document rather than an opinion.
The first is an inventory of every named or identifiable real person, with the passages that make factual claims about them marked. Whether those passages can be published is a question for a lawyer, and copyright is not the relevant law. The Copyright Office states that copyright does not protect ideas, facts, titles, names, short phrases, and slogans.3 The exposure comes from defamation and privacy law instead.
The second is an inventory of quoted material. Song lyrics, poems, unpublished letters, diaries, photographs, and maps each carry their own permission question. The Copyright Office is explicit on the point. No formula ensures that a predetermined percentage or amount of a work, or a specific number of words, lines, pages, or copies, may be used without permission.4 Fair use is decided on four factors weighed together. They are the purpose and character of the use, the nature of the work used, the amount and substantiality of what was taken, and the effect on the market for the original.4
The third is a list of every external fact the book asserts. Each is checked where a reference work can settle it, and flagged where none can.
Where disguise breaks down, and what an editor sees that an author does not
Changing a name protects nobody on its own. A changed name attached to an unchanged job, town, and family structure identifies the same person to everyone who knows them.
What an editor can supply is the list. Every identifying detail attached to a disguised figure can be collected in one place: name, age, occupation, location, relationships, and distinguishing events. Authors are usually the last people able to see that list, because they know who the person is and read the disguise as complete. Seeing the details gathered is what tells an author whether the disguise is real or nominal.
The craft cost is real and belongs in the same conversation. Composite characters flatten timelines, moved locations break geography, and altered relationships can remove the reason a scene matters. An editor can say which scenes stop working, which is a different thing from advising an author to take the risk.
What stays with the author
Whether a passage is defamatory, whether a use is fair, and whether a book is safe to publish are questions for an attorney. An editor who answered them would be practicing law, and the fact that the answer often seems obvious is not a reason to give it.
Everything a client sends is treated in confidence, including unpublished manuscripts, correspondence, and material about living people. EditFast works on memoir and autobiography and on fiction alike, and supplies the inventories described above with the edited manuscript.
Authors who commission that work early usually spend less on it. Permissions take months, and a book that reaches typesetting with three uncleared quotations has a production problem rather than an editorial one.