Comments in blue are from debatingchristianity.com:
“It must be noted that the term 'Adonay' in [Ps. 110:5] was changed from ‘Jehovah’ by the Sopherim during the corrupted temple era. This is a known perversion of the original Hebrew scripture and was carried on later by the Mazoretes into modern extant copies. ….
“Therefore, verse 5 should read: "..the Jehovah on your right.." and we can resolve the Adon in verse 1 to a second Jehovah who is beckoned to sit at the right hand of the first Jehovah. This is later confirmed in Acts 5:31, Romans 8:34, and Hebrews 10:12. Jehovah should then be known as the family surname of the biblical Elohim made up of the Son, Jehovah on the right; and the Father, Jehovah on the left. This conclusion is inescapable, and is the only rational result from scripture.”
John Gill's Exposition of the Entire Bible tells us at Psalms 110:5 that the words “The Lord at thy right hand,.…” may have several interpretations. The first one listed by him is that these words are directed to Christ, at whose right hand the Lord [Jehovah] was to help and assist him, Ps. 16:8"
Ps. 110:5 "The Lord at thy right hand shall strike through kings in the day of his wrath." Now that he has come into the field of action, the infinite Jehovah comes with him as the strength of his right hand.” - The Treasury of David.
“The Lord [Jehovah], says Psalm 110:5, dashes in pieces kings at the right hand of this priest-king [Christ], in the day when His wrath is kindled (Psalm 2:12, cf. Psalm 21:10). ['Lord’] is rightly accented as subject. The fact that the victorious work of the person addressed is not his own work, but the work of [Jehovah] on his behalf and through him, harmonizes with Psalm 110:1.” - Keil and Delitzsch Biblical Commentary on the Old Testament.
“5. at thy right hand-as Ps 109:31, upholding and aiding, which is not inconsistent with Ps 110:1, where the figure denotes participation of power, for here He is presented in another aspect, as a warrior going against enemies, and sustained by God.” - Jamieson-Fausset-Brown Bible Commentary
Further comment by above poster on debatingchristianity.com: “In fact, the name Jehovah itself is a family surname like my surname is Jones.”
But here are the facts about surnames in the OT:
sur'-nam (kanah; epikalein): A word derived from the French., meaning ‘an additional name’; in modern English always the family name of a person. Indeed, the spelling ‘surname’ in the King James Version 1 Macc 1:10; 2:2; 6:43 may be due to a confusion with ‘sire's name.’ But the custom of family names was entirely unknown among the Hebrews. The word is used twice in the King James Version of the Old Testament, namely, Isa 44:5; 45:4. The Hebrew word means ‘to give flattering or honorary titles.’ In the former passage foreigners are so envious of the prosperity of the Jews that they are anxious to be surnamed by the name of Israel, i.e. to be enrolled as members of the Jewish nation. In the latter case Yahweh gives Cyrus an honorary title, namely, ‘servant of Yahweh,’ and thus appoints him to be His instrument in the restoration of His people. The same word is rendered in Job 32:21, the King James Version, ‘give flattering titles.’ Elihu declares his intention to examine the situation without fear or favor. He will not allow such high-sounding titles as ‘Your Worship’ or ‘My Lord’ to stand in his way. He will not be overawed by Job's social position. ….” - p. 2872, Vol. IV, International Standard Bible Encyclopedia, Eerdmans Publ., 1984. (Also see p. 481, Vol. 3, “Name,” A Dictionary of the Bible, Hastings - Hendrickson Publishers, 1988 reprint.)