Those phrases are all easy to understand. When it comes to "one of," some speakers immediately substitute it with the possessive and think, "One of my sisters' [Barbara's] friend is in town," which is incorrect. For it to be grammatically correct, "one of" must refer to a plural possessed object "friends" rather than "sisters."
In sum, when one incorrectly identifies the object in the prepositional phrase "one of," then it becomes a problem.
I'm at a loss as to how someone could get that from the sentence. The subject of the sentence reduces to the pronoun "one," modified by the prepositional phrase "of my sister's friends." "One" as a pronoun refers to part of a group or number, so should not be modified by a singular prepositional object. The only possessives, "my" and "sister's," modify "friends." As opposed to "one" in a sentence like "One friend was an actress," where "one" is an adjective modifying "friend," the subject.