Let’s review possessives. Keep in mind I’m a Chicago gal (as in Chicago Manual of Style) so I use their conventions. If you use a different style guide, you can find those guidelines in your manual.
Michael Jones owns a car. It’s Michael Jones’s car. (Add the ‘s. You say it when you speak, so type or write it, too.)
Michael and Sarah Jones own a house together. It’s the Joneses’ house. (Joneses is the plural of Jones. Add just an apostrophe, because plural possessives don’t take the additional S.
Michael’s work is Mr. Jones’s job. Sarah’s is Mrs. Jones’s job.
And I’ll bet they have separate toothbrushes, so there’s Michael’s and Sarah’s toothbrushes. BUT, they probably own the TV in the parlor jointly, so that’s Michael and Sarah’s TV. (Or Sarah and Michael’s TV. Let them sort that out.)
If they have a friend named Jesus Garcia, and he’s got a car too, that’s Jesus’s car. If you’re talking about the Biblical figure Jesus, you don’t add the S; that’s considered a “classical or historical name,” and those take just the apostrophe. Moses’ tent. Xerxes’ troops. Jesus’ birth.
And I’ll leave it at that. If you have questions, comment and I’ll respond as I have time. It’s copy-editing day here.