Thought this might be useful for anyone else who has a name for their baby that ends in S. We have a professional editor friend, so DH asked what's the norm these days with the possessive form of a name ending in S. I hadn't known if trends had changed since I went through school. She said:
"That's a good question. Style manuals disagree, so I think you're on
safe grounds to choose which you prefer. However, there's more support
for Silas's.
The Associated Press Stylebook 2011 (journalism) would say Silas'. The Chicago Manual of Style (more formal prose and books) would say Silas's. The Gregg Reference Manual (business) gives this guideline: "To form the possessive of a singular noun that ends in an s
sound, be guided by the way you pronounce the word. If a new syllable
is formed in the pronunciation of the possessive, add an apostrophe plus
s. (Mr. and Mrs. Morris's plane tickets . . . Dallas's business district)."
Re: Possessive form of "Silas"
ETA: I was a journalism major in college, so it makes sense that I would cling to the AP style on this issue.