Apostrophes can be confusing. I get it. Grammar can be confusing, the English language is confusing! It’s enough to make you want to pull your hair out.
Deep breath, it’s OK. There are these wonderful things called STYLE MANUALS that help us editors keep everything strait. Some people think style manuals are outdated and irrelevant. Editors and proofreaders rely on them as a set of industry standards to keep everything common. If everyone goes off and does their own thing, it gets all confusing and some people read words one way, and other people read it another way. That is why we have STANDARDS, so everyone is on the same page.
With Apostrophes all the style manuals say the same thing. Regardless of what letter the word ends with, if the word is singular ADD (‘s). Example. “Ella and her blanket.” Ella is singular, there is only one Ella. “Ella’s blanket.” “Alexis has a flower.” Alexis is singular “Alexis’s flower.” Writing Alexis’ flower says that there are more than one Alexises (Alexi?).
For plural words still add (‘s) UNLESS the PLURAL word ends in s, then just add (‘).
“The four dogs all have bones. Those are the dogs’ bones.” “The mice all had a piece of cheese. The mice’s cheese.”
As you can see, the industry standards may see funny and some people may not like them, but they are necessary for everyone to understand what is being said in our writing.
As always, if you need help or copyediting services, feel free to contact me!