The other day a reader contacted me to ask why I referred to my blog as Nick Daws' Writing Blog. She felt it should really be Nick Daws's Writing Blog.
The question of how you turn a name ending in an 's' into a possessive is one that crops up quite regularly. Like many such issues, there is no clear right or wrong answer.
The rule I have always followed is that either option is acceptable, and it really comes down to how you want it pronounced.
In my case, I would much prefer to have my blog's name pronounced "Nick Daws Writing Blog" than adding an unnecessary extra syllable to make it "Nick Dawsiz Writing Blog" (excuse my phonetic spellings). For that reason, I prefer it as Nick Daws' Writing Blog.
On the other hand, there are plenty of occasions when I prefer the apostrophe-s ending. For example, in a short story I was reading recently about Wallis Simpson, I came across the sentence, "It was as though a veil of composure had passed instantaneously over Wallis' previously fraught and tense face."
I would have written Wallis's here, as that is how I would pronounce it. "Over Wallis previously fraught and tense face" (again writing phonetically) just doesn't sound right to me, though I'd never say it was definitely wrong. The problem I have with it is that it immediately strikes me as odd, and because of that I am temporarily propelled out of the story to ponder matters of grammar and punctuation.
There can also be house style considerations. AP style favours leaving off the extra 's', for example, while the Oxford Manual of Style recommends adding it. The excellent Grammar Girl website had a useful discussion on this point a while ago.
This is therefore one of those issues where it is impossible to be correct in everyone's eyes all of the time. Unless you are instructed to follow a particular house style guide, therefore, my advice is to consider which version sounds more natural and more euphonious, and punctuate according to this. And, obviously, be consistent when using the same phrase later in the same work.
And yes, I am happy to confirm that I will be using the version Nick Daws' Writing Blog for the foreseeable future!