“There is a long tradition of conservative circles fretting about international influences on the German languages,” said Stefanowitsch. “It used to be French, and now it’s mainly English”.

Heh.

The problem with defending the purity of the English language is that English is about as pure as a cribhouse removed. We don’t just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary.

–James Nicoll

However, guidelines issued by the body regulating the use of Standard High German orthography have clarified that the use of the punctuation mark colloquially known as the Deppenapostroph (“idiot’s apostrophe”) has become so widespread that it is permissible – as long as it separates the genitive ‘s’ within a proper name.

Hmm.

So how do they deal with the more-complex cases?

https://www.thesaurus.com/e/grammar/whats-the-rule-for-doing-a-possessive-after-the-word-s/

Singular nouns ending in S

Rule 1: In general, you form a possessive singular noun (both proper and common) by adding an apostrophe and the letter S to the end of the word.

• the flower’s petals

• Riley’s car

That’s simple enough. It’s when the car belongs to a person named Chris, or we’re talking about the petals of a crocus that the rules get blurry. Most experts and guides say you should add an apostrophe and an S to both proper and common nouns to make them possessive even when they end in S. So, using the examples above, it would be:

* Chris’s car

• the crocus’s petals

Not everyone agrees with this method, however, and some, such as the Associated Press Stylebook, nod in favor of adding only an apostrophe to make a proper noun possessive, such as:

• Chris’ car

• Dickens’ novels

To add even more confusion, AP Style also has an exception if the word following the possessive starts with an S, stating that in those cases only the apostrophe should be added. So it would be:

• Texas’s people

Texas’ streams

In 2019, the AP raised quite the ruckus when they tweeted that they were considering adding an S after the apostrophe for singular proper nouns, as in Mavis Staples’s album or Martha Reeves’s concert. To date, no changes have been made, but as you can see, it’s an ever-evolving, highly volatile topic.

Plural nouns ending in S

Rule 2: Plural nouns, on the other hand, generally don’t get an extra S, just an apostrophe. Most experts suggest you form the plural form of the word first, then add the apostrophe.

For example:

• the Joneses’ house

• the classes’ rules

Most say possessive words should generally read as you would speak them.

The one-syllable rule

When it comes to historical proper names or those found in the Bible, however, there is another rule many choose to follow.

Rule 3: According to some, those words with two or more syllables typically just get an apostrophe after the final S, while one-syllable words getting both an apostrophe and an S.

For example:

• Jesus’ teachings

• Zeus’s temper

Some people apply it to more recent names as well, such as Dr. Seuss’s writings or Kenny Rogers’ songs, while others believe they all should also get an additional S.

Singular nouns in plural form

Rule 4: When it comes to singular nouns that are plural words, they typically just get the apostrophe.

For example, the Beatles is a singular noun, but it’s in the form of a plural word. So, it would be:

• The Beatles’ album

For the sake of …

Rule 5: Whether a noun ends in an S or not, if it’s followed by the word sake, most say it just gets an apostrophe.

For example:

• for goodness’ sake

• for conscience’ sake

• for appearance’ sake

Others, such as the Chicago Manual of Style, say if the word before sake ends in an S, then it should just get an apostrophe. Others should get an apostrophe and an S. So, it would be:

• for goodness’ sake

• for conscience’s sake

• for appearance’s sake

Like, there’s a whole rabbit hole to go down there.