Boccur makes an interesting case. But he'll have to do better than that to convince me to substitute an OG reading for a MT reading. There's a reason why Theodotion's version of Daniel supplanted the OG version. And if we get into the identity of Father and Son and the Trinitarian controversy, that would take us into the first few Christian centuries, which is very late in the game. Here's Dan. 7:13, 14 in the Gottingen Septuagint, the phrase in question glaring in its absence. Who am I to question such specialists?
13 om. τῆς νυκτός 62′ | μετά = Marc. 14:62 Apoc. 1:7] επι Q Sa Hippol.Ant.HS Eus.ecl. Chr. (= I828) PsChr. II799 Tht. IV524 = οʹ et Matth. 24:30 26:64 | ὡς Cyr.VIII648] ωσει 62′ 449 C′−87 26 46′ 106 407 590 Cyr. III1048 | ἐρχόμενος B-26-46′-239 Q V 538 LaS Hippol. Eus.dem. p. 440, 10 et ecl. CyrHieros. p. 909 Didym. p. 893 PsAth.IV697 Chr.I828 VII553 PsChr. II799 Cyr. I313 IX933 X309 Hil. Aug.ep. 198, 3] + ην A′’ L’-311 C′ 230′’ 407 534 590 Arab Eus.dem. p. 495, 23 et eccl. theol. et c. Marc. Chr. (= I294) Tht. Cyr. VI284 VIII 648. 1048 Aug. civ. 18, 34 = 𝔐; + αυτος ην 62′; ηρχετο Tht. IV524 = οʹ; venit verss.p Lucif.; veniebat Vig. c. Eut. 1, 14 PsVig. c. Var. 1, 47 | om. καὶ προσήχθη αὐτῷ Aeth Eus.dem. p. 440, 10 CyrHieros. p. 909 Tht.IV524 PsVig.; om. καί A’ | προσήχθη αὐτῷ B-46′ Q* LaS Hippol.Ant.p Didym. Lucif. Hil. PsVig. trin. 3] προσηνεχθη αυτω Qc Hippol. p. 210, 18 et Ant.p Eus.dem. p. 495, 24 et ecl. et eccles. theol. PsAth. IV697 = Sixt.: cf. Is. 53:7 σʹ; αυτω προσηνεχθη 230; ενωπιον (εμπροσθεν Eus.) αυτου προσηνεχθη (+ αυτω 62′ 311-lII Chr. Tht.p) O L′’ C′ 106 233′ 393 407 534 590 Co Arab Arm Eus. c. Marc. Chr. (= I 294. 828) Tht. Cyr. I 313 VI 284 VIII 648. 1048 IX 933 X 309 Aug. civ. 18, 34; ενωπιον αυτου (+ και 584) προσηγαγον αυτον A’ 26 = 𝔐; pr. ενωπιον αυτου 239
14 αὐτῷ ἐδόθη] tr. verss.p Hippol.Ant.p Eus.dem. p. 495 et ecl. Cyr. I 313 Lucif. Hil. = οʹ | ἀρχή … τιμή] tr. 311 CyrHieros. p. 909 Tht.p; αρχη … εξουσια Sa; εξουσια … τιμη Eus.ecl.: cf. οʹ | γλῶσσαι] pr. και B 538 106 verss.p Hippol.p Hil. PsVig. trin. 3 = 𝔐: cf. 3:4 | δουλεύσουσιν αὐτῷ Q-233 46′ 590 Co Aeth Arab Hippol. Eus.ecl. Didym. p. 893 PsAsAth. IV 697 Hil. PsVig. trin. 3] δουλευουσιν αυτω B-239 LaS CyrHieros. p. 909 Lucif.; αυτω δουλευουσιν A’ 538-88 c Eus.dem. Chr. I 294; αυτω δουλευσουσιν (-σωσιν 62′ 230) O L-311-449 C 26 106 230’ 393 (+ και υπακουσονται: ex 27) 407 534 Arm Eus. eccl. theol. et c. Marc. Chr. (= I 828) Cyr. VI 284 VII 656 VIII 648. 1048 IX 933 X 309 Tht. Aug. civ. 18, 34 = 𝔐: cf. 27 | ἡ ἐξουσία] αυτω ουσια 534; pr. και L’-311 LaS Aeth Arab Arm Tht. Ir.lat Lucif. Hil. = οʹ | ἐξουσία1°◠2° 88 | om. καὶ ἡ βας. αὐτοῦ οὐ διαφθ. 230: homoiot.; om. καί LaS | οὐ ult.] pr. η V Aeth = 𝔐
Joseph Ziegler, Olivier Munnich, and Detlef Fraenkel, eds., Susanna, Daniel, Bel et Draco, vol. XVI, 2, Vetus Testamentum Graecum. Auctoritate Academiae Scientiarum Gottingensis Editum (Göttingen: Vandenhoeck & Ruprecht, 1999), 339–341.
In the Foreword to Daniel Pietersma explains: "It is not until 7-12 that one generally finds the common vocabulary in the two Greek versions to run around 50% and portions (e.g., 7.10, 25; 8.11-17, 21-23; 9.3-4, 11-12, 19-20, 27; 10.3-6, 19-20; 11.38) where there is extensive argreement for a verse or more. Some of the places where there is agreement can be demonstrated to be due to textual corruption, while others are incidental agreements that would be expected from two independent translators working from a similar source text. However, the portions of the Greek versions in these chapters where the verbal agreements between the texts are strong give the appearance that the TH text is a revision of the OG."