I hope the following will settle the issue as to whether to use 's or s' with regard to names.
How to use Apostrophes
5. When names end with the letter 's', either use is acceptable:
James' wife or James's wife.
(It is often said that the choice between the two should be made on how the word is pronounced.)
Some words sound awkward when an apostrophe 's' is added:
Jesus's disciples.
The accepted form here is to just use the 's' apostrophe:
Jesus' disciples.
N.B. This only applies to names of Biblical or historical significance e.g. Jesus, Moses, Zeus, Demosthenes, Ramses ... the rest of us whack in the apostrophe and add an 's.'
Moses' followers, Zeus' priests, Demosthenes' teachings, Ramses' pyramid
Others don't have the same clumsy sound:
The princess's chair.