I am completely lost and I need help

When I added the 7th emerald to my hack, I took a different approach. The original code, as you mentioned, actually relies on the emeralds to be consecutive, yes, but you can change this behaviour by changing the way d4 gets valorised.
In short, since I didn't plan to use the 1-up object, I changed its behaviour to work as the 7th emerald. You can do the same if you don't plan to use the 1-up object. The advantage is that the 1-up object is naturally collectable so you don't have to do major modifications of the code.
In short, something like this:

Code (Text):

1. Obj09_Chk1Up:
2.         cmpi.b    #$28,d4    ; is the item an extra life? (NOW 7TH EMERALD)
3.         bne.s    Obj09_ChkEmer
4.         bsr.w    SS_RemoveCollectedItem
5.         bne.s    Obj09_GetEmer2
6.         move.b    #5,(a2)
7.         move.l    a1,4(a2)
8. Obj09_GetEmer2:
9.         cmpi.b    #7,($FFFFFE57).w; do you have all the emeralds?
10.         beq.s    Obj09_NoEmer; if yes, branch
11.         move.b    #$6,d4    ; EMERALD NUMBER :o
12.         moveq    #0,d0
13.         move.b    ($FFFFFE57).w,d0
14.         lea    ($FFFFFE58).w,a2
15.         move.b    d4,(a2,d0.w)
16.         addq.b    #1,($FFFFFE57).w; add 1 to number of emeralds
17.         bra.s    Obj09_NoEmer
18.  
19. ;===========================================================================
20.  
21. Obj09_ChkEmer:
22.         cmpi.b    #$3B,d4    ; is the item an emerald?
23.         bcs.s    Obj09_ChkGhost
24.         cmpi.b    #$40,d4
25.         bhi.s    Obj09_ChkGhost
26.         bsr.w    SS_RemoveCollectedItem
27.         bne.s    Obj09_GetEmer
28.         move.b    #5,(a2)
29.         move.l    a1,4(a2)
30.  
31. Obj09_GetEmer:
32.         cmpi.b    #7,($FFFFFE57).w; do you have all the emeralds?
33.         beq.s    Obj09_NoEmer; if yes, branch
34.         subi.b    #$3B,d4
35.         moveq    #0,d0
36.         move.b    ($FFFFFE57).w,d0
37.         lea    ($FFFFFE58).w,a2
38.         move.b    d4,(a2,d0.w)
39.         addq.b    #1,($FFFFFE57).w; add 1 to number of emeralds
40.  
41. Obj09_NoEmer:
42.         move.w    #$93,d0
43.         jsr    (PlaySound_Special).l;    play emerald music
44.         moveq    #0,d4
45.         rts

Emphasis on move.b #$6,d4

 

Maybe theres already an object in slot $39?

EDIT:

Code (ASM):

1.  
2. Obj09_GetEmer:
3.         cmpi.b  #7,($FFFFFE57).w ; do you have all the emeralds?
4.         beq.s   Obj09_NoEmer    ; if yes, branch
5.         subi.b  #$3B,d4                   ; did you change this line to $3A?
6.  

Do it, it might work.

 

Yes, it's the unused number 6 object (see picture below), but I assume that Quickman already changed that.


edit:

You obviously have no idea of what that line is supposed to do. Look at these instructions:

Code (Text):

1.         move.b    ($FFFFFE57).w,d0
2.         lea    ($FFFFFE58).w,a2
3.         move.b    d4,(a2,d0.w)

So here's what happens.
At the start of the routine, d4 contains the object number. Emeralds are from $3B to $40. So by subtracting $3B from d4 you obtain the emerald number (basically, the color) in a 0-5 range.
move.b ($FFFFFE57).w,d0 puts the number of collected emeralds into d0
lea ($FFFFFE58).w,a2 puts "$FFFE58" into address register a2.
Then there is move.b d4,(a2,d0.w)
Remember, d4 by now contains the number (or the "color") of the emerald you just collected (0 = blue, etc). The move.b puts that emerald number into $FFFE58 + d0
Basically the ram is sorted like this in Sonic 1:
FE57 = number of emeralds you collected
FE58 = "color" of the first emerald you collected
FE59 = "color" of the second emerald you collected
FE5A = "color" of the third emerald you collected
etc.

This incidentally leads to the bug which allows you to collect 6 blue emeralds if you put FE57 = 6 and keep the following bytes at 0.
By changing the line you wanted to change you would obtain no effect whatsoever other than referencing wrong emerald colors.