I am doing a super hard Super Sudoku. In the very bottom right cell, r16c16, I got 7, D or E. Above it, in same column I got a D or E, and to the left of the r16c16, I got a 7 or D.

Based on lock pairs, if they were in same row or column, I could erase all 7, D and E's from that row/column.

Question 1:

I am wondering if that same thing works even if all three aren't in same row/column? Where boxes labeled 2 and 3, are connected to box labeled 1.

1= 7DE

2 = 7D

3 = DE

Question 2:

Also, I was wondering if locked pairs work, even if in sets of 3, and odd number? I got 3 boxes with DE's, if you look at the DE labeled 3 on picture, below it I got a box with 1, 3, 7, D or E, to the left of that box is another DE. Based on DE being in same row, and same column, doesn't that mean I can erase the DE from the 137DE box?? I have this exact same thing on the other side of the puzzle, where I got a set of three boxes in same positions as the DE's but they are OA, but where 137DE is, on this other setup, I got a box with OAC.

My problem is, I looked at answer sheet, and I know for a fact that DE is not in the 137DE box, and that OA is not in the OAC box. But I thought it might be coincidence, I just wanted reassurance that it is a real move, and not just coincidence.

Question 3:

In a house not shown, I got 4 boxes left, I got 2 boxes with 37C, I then got a 3rd box with 357C, and a last box with 57C. With the two being 37C, and a 3rd box having those three numbers in it, does that allow me to erase the 7C from the 57C box?