The Charles Tavis relation — stepbrother, half-brother, or adoptive brother?

texture · UNDATED (Avril's girlhood, B.S. era), disputed

• When: UNDATED (Avril ~8+ when her father remarries; the relation is stated variously throughout)
• What: Per Orin (Hal's sole source, scene 170): after Avril's mother died, her father left the potato farm on "business," was gone weeks, and returned with an American widow, Elizabeth Tavis — who "seems almost certainly to have been a dwarf" (achondroplastic) in the Vermont wedding photo — whose infant son by a dead ne'er-do-well was Charles Tavis. On this account C.T. is "probably not related to the Moms by actual blood." The novel never fixes the relation: C.T. is called JOI's "half-brother-in-law" (020), Avril's "adoptive brother" (013, 102), her "half-brother" (071), "adoptive-slash-half-brother" (068), and "either Mrs. Incandenza's half-brother or adoptive brother, depending on the version" (026). Avril and C.T. "have never represented themselves as anything other than unrelated but extremely close." This ambiguity underwrites the Avril-C.T. crux (event 30). Cite all versions as written.