Who was the second witness that Yeshua "came to fulfill the law and the prophets"?
" " to Hosea 3?
Luke 1 describes Luke obeying Dt by getting more eyewitnesses to the events HE saw!!
You might want to reread Luke 1:1-3. You are adding to what is written. And apart from Paul's sole testimony, he saw or heard nothing from Yeshua. A sole testimony makes that statement "untrue" (John 5:31) And who is "Mark", and was he a witness to anything he describes? Were there things added to and subtracted from the message of Yeshua?
Luke 1:1 Inasmuch as many have undertaken to compile an account of the things accomplished among us, 2 just as they were handed down to us by those who from the beginning were eyewitnesses and servants of the word, 3 it seemed fitting for me as well, having investigated everything carefully from the beginning, to write it out for you in consecutive order, most excellent Theophilus; 4 so that you may know the exact truth about the things you have been taught.