Note: here is a tentative proposal. There seem to be book ends with reference to the chief priests and scribes in verse 1 and 19.
A. 1 And it came to pass, that on one of those days, as he taught the people in the temple, and preached the gospel, the chief priests and the scribes came upon him with the elders,
1A. 2 And spake unto him, saying, Tell us, by what authority doest thou these things? or who is he that gave thee this authority?
1B. 3 And he answered and said unto them, I will also ask you one thing; and answer me:
1C.a. 4 The baptism of John, was it from heaven,
b. or of men?
1C’. a’. 5 And they reasoned with themselves, saying, If we shall say, From heaven; he will say, Why then believed ye him not?
b’. 6 But and if we say, Of men; all the people will stone us:for they be persuaded that John was a prophet.
1B’. 7 And they answered, that they could not tell whence it was.
1A’. 8 And Jesus said unto them, Neither tell I you by what authority I do these things.
2A. 9 Then began he to speak to the people this parable; A certain man planted a vineyard, and let it forth to husbandmen, and went into a far country for a long time.
2B. 10 And at the season he sent a servant to the husbandmen, that they should give him of the fruit of the vineyard: but the husbandmen beat him, and sent him away empty. 11 And again he sent another servant: and they beat him also, and entreated him shamefully, and sent him away empty. 12 And again he sent a third:and they wounded him also, and cast him out.
2C. 13 Then said the lord of the vineyard, What shall I do? I will send my beloved son: it may be they will reverence him when they see him.
2B’. 14 But when the husbandmen saw him, they reasoned among themselves, saying, This is the heir:come, let us kill him, that the inheritance may be ours. 15 So they cast him out of the vineyard, and killed him.
2A’. What therefore shall the lord of the vineyard do unto them? 16 He shall come and destroy these husbandmen, and shall give the vineyard to others. And when they heard it, they said, God forbid. 17 And he beheld them, and said, What is this then that is written, The stone which the builders rejected, the same is become the head of the corner? 18 Whosoever shall fall upon that stone shall be broken; but on whomsoever it shall fall, it will grind him to powder.
A’. 19 And the chief priests and the scribes the same hour sought to lay hands on him; and they feared the people: for they perceived that he had spoken this parable against them.