A.T. Robertson Commentary Philemon 1:2

"and to Apphia our sister, and to Archippus our fellow-soldier, and to the church in thy house:" — Philemon 1:2 (ASV)

To Apphia our sister (Απφια τη αδελφη). Dative case in address. A common name in Phrygian inscriptions and apparently the wife of Philemon. "Sister" is in the Christian sense.

To Archippus (Αρχιππω). Dative case in address. It is uncertain whether he is the son of Philemon or not. Apparently he is prominent in the church in Colossae, possibly even pastor, probably not in Laodicea as some understand Col 4:17 to imply.

Fellow-soldier (συνστρατιωτη). Old word, only here and Php 2:25 in N.T. In metaphorical sense. Perhaps while Paul was in Ephesus.

To the church in thy house (τη κατ' οικον σου εκκλησια). The church that met in the house of Philemon. In large cities there would be several meeting-places. Before the third century there is no certain evidence of special church buildings for worship (White, Exp. Grk. T.). See Ac 12:12 for Mary's house in Jerusalem, 1 Corinthians 16:19 for the house of Aquila and Prisca in Ephesus, Romans 16:5 for the house of Prisca and Aquila in Rome, Colossians 4:15 for the house of Nympha in Laodicea.