I’ve tried my best to find out, who is this descendant (Aminadi) of Amulek? Footnote 10:2a Dan. 5:16. Is Aminadi Daniel?
I too have wondered about Aminadi and the writing on the wall of the temple. Unfortunately, as Daniel H. Ludlow explains, we just don’t know anything more:
“In his introduction, Amulek mentions he is ‘the son of Giddonah, who was the son of Ishmael, who was a descendant of Aminadi . . . who interpreted the writing which was upon the wall of the temple, which was written by the finger of God.’ (Alma 10:2) This is the only time Aminadi is mentioned, and our present Book of Mormon gives no further details concerning the writing written by the finger of God upon the wall of the temple. Evidently an account of this incident was recorded on the large plates of Nephi, but Mormon did not include it in his abridgment.” (Daniel H. Ludlow, A Companion to Your Study of the Book of Mormon, p. 198.) Book of Mormon (Religion 121-122) Student Manual, copyright 1979, 1981
The footnote you mention links to a similar event, not to the same person, nor to this specific event. As mentioned in verse 3 of Alma 10, Aminadi is descended from Nephi the son of Lehi:
Alma 10:2 I am Amulek; I am the son of Giddonah, who was the son of Ishmael, who was a descendant of Aminadi; and it was that same Aminadi who interpreted the writing which was upon the wall of the temple, which was written by the finger of God.
3 And Aminadi was a descendant of Nephi, who was the son of Lehi, who came out of the land of Jerusalem, who was a descendant of Manasseh, who was the son of Joseph who was sold into Egypt by the hands of his brethren. Alma 10:2-3
Daniel, on the other hand, was carried away into Babylon some time after Lehi and his family began their trip to the promised land (according to the Bible Dictionary, Nebuchadnezzar reigned in Babylon circa 604–561 B.C.):
1 In the third year of the reign of Jehoiakim king of Judah came Nebuchadnezzar king of Babylon unto Jerusalem, and besieged it.
2 And the Lord gave Jehoiakim king of Judah into his hand, with part of the vessels of the house of God: which he carried into the land of Shinar to the house of his god; and he brought the vessels into the treasure house of his god.
3 ¶ And the king spake unto Ashpenaz the master of his eunuchs, that he should bring certain of the children of Israel, and of the king’s seed, and of the princes;
6 Now among these were of the children of Judah, Daniel, Hananiah, Mishael, and Azariah: Daniel 1:1-3,6
As you can see, Daniel was in a different place and of a different generation than Aminadi. They simply share similar experiences with writing on a wall (of the temple for Aminadi, and of the king’s palace for Daniel), but nothing more. I hope that helps – even if it leaves us both wishing for the rest of the story.