Greek Article, scenarios Acts 15:22-26

A single article with two nouns/substantives joins them into a single scenario. This is illustrated more than once in Acts 15:22-26:

Acts 15:22   Then it seemed good to the apostles and the elders, with the whole church, to choose men from among them and send them to Antioch with Paul and Barnabas. They sent Judas called Barsabbas, and Silas, leading men among the brethren,  23 with the following letter:  “The brethren, both the apostles and the elders, to the brethren who are of the Gentiles in Antioch and Syria and Cilicia, greeting.  24 Since we have heard that some persons from us have troubled you with words, unsettling your minds, although we gave them no instructions,  25 it has seemed good to us, having come to one accord, to choose men and send them to you with our beloved Barnabas and Paul,  26 men who have risked their lives for the sake of our Lord Jesus Christ. 

22 Τότε ἔδοξε τοῖς ἀποστόλοις καὶ τοῖς πρεσβυτέροις σὺν ὅλῃ τῇ ἐκκλησίᾳ ἐκλεξαμένους ἄνδρας ἐξ αὐτῶν πέμψαι εἰς Ἀντιόχειαν σὺν τῷ Παύλῳ καὶ Βαρναβᾷ, Ἰούδαν τὸν καλούμενον Βαρσαββᾶν καὶ Σιλᾶν, ἄνδρας ἡγουμένους ἐν τοῖς ἀδελφοῖς,  23 γράψαντες διὰ χειρὸς αὐτῶν· Οἱ ἀπόστολοι καὶ οἱ πρεσβύτεροι ἀδελφοὶ τοῖς κατὰ τὴν Ἀντιόχειαν καὶ Συρίαν καὶ Κιλικίαν ἀδελφοῖς τοῖς ἐξ ἐθνῶν χαίρειν.  24 Ἐπειδὴ ἠκούσαμεν ὅτι τινὲς ἐξ ἡμῶν [ἐξελθόντες] ἐτάραξαν ὑμᾶς λόγοις ἀνασκευάζοντες τὰς ψυχὰς ὑμῶν οἷς οὐ διεστειλάμεθα,  25 ἔδοξεν ἡμῖν γενομένοις ὁμοθυμαδὸν ἐκλεξαμένοις ἄνδρας πέμψαι πρὸς ὑμᾶς σὺν τοῖς ἀγαπητοῖς ἡμῶν Βαρναβᾷ καὶ Παύλῳ,  26 ἀνθρώποις παραδεδωκόσι τὰς ψυχὰς αὐτῶν ὑπὲρ τοῦ ὀνόματος τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ.

Two groups of church leaders are mentioned in v22 and both are given an article τοῖς ἀποστόλοις καὶ τοῖς πρεσβυτέροις. The ἀπόστολοι and the πρεσβύτεροι are portrayed here as opening distinct scenarios, probably because the ἀπόστολοι had higher level of authority and a different function within the church. In verse 23 this pattern is repeated Οἱ ἀπόστολοι καὶ οἱ πρεσβύτεροι ἀδελφοὶ, they are all brethren but the groups as distinguished. But the addressees that follow are all joined together under one article τοῖς κατὰ τὴν Ἀντιόχειαν καὶ Συρίαν καὶ Κιλικίαν ἀδελφοῖς, these brethren are from various places but are considered here as one group, without distinctions.   

In verse 22 Paul and Barnabas are joined under a single article τῷ Παύλῳ καὶ Βαρναβᾷ indicating that for the purpose of this narrative their ministry invokes a single scenario. When they are named again in verse 25 they are included in the construction σὺν τοῖς ἀγαπητοῖς ἡμῶν Βαρναβᾷ καὶ Παύλῳ where τοῖς appears to govern the entire construction.  A similar pattern from Eusebius:

Eusebius Historia ecclesiastica
Book 7, chapter 5, section 6, line 2

καὶ μεθ' ἕτερά φησιν.
 »καὶ τοῖς ἀγαπητοῖς δὲ ἡμῶν καὶ συμπρεσβυτέροις Διονυσίῳ καὶ Φιλήμονι, συμψήφοις πρότερον Στεφάνῳ γενομένοις καὶ περὶ τῶν αὐτῶν μοι γράφουσιν, πρότερον μὲν ὀλίγα, καὶ νῦν δὲ διὰ πλειόνων ἐπέστειλα».      

I am somewhat uncertain about how to analyze this in terms of scenarios. I would suggest that this opens a single scenario, the unified scenario is indicated by the attributives ἀγαπητοῖς and συμπρεσβυτέροις. The pattern: plural-dative-article plural-dative-adjective proper-name (noun dative singular) καὶ proper-name (noun dative singular) is not difficult to read but the presence/absence of the article with the proper names is dictated by the syntax of attributive adjectival constructions. Making one or both of the proper-names articular changes the syntax of the adjective noun construction. So we cannot treat the proper-names in this construction as we would in τῷ Παύλῳ καὶ Βαρναβᾷ in verse 22.

The two men sent in verse 22 were Judas called Barsabbas, and Silas. They were both “leading men among the brethren” but no article appears so we should not assume that they were considered somehow as a team like Paul and Barnabas.