Set Composites with 1966 Kennedy Half SMS DDO

ProofCollection

First off, I am not a Kennedy Half Dollar expert so I don't really have any background on this which is why I'm asking this.

Currently, the following set registries (and possibly more), have a 1966 SMS DDO slot that specifies FS-103:
Kennedy Half Dollars with Major Varieties, Proof (1964-Present)
Kennedy Half Dollars with Major Varieties, Circulation Strikes and Proof (1964-Present)
Kennedy Half Dollars with Major Varieties with 1964 SMS, Circulation Strikes and Proof (1964-Present)

How and who decided that FS-103 is the only FS# valid for this slot? And would it be valid to allow FS-106? FS-106, from what I can see/tell, appears to be far more interesting.
From Variety Vista:
FS103:

FS106:

Tom147

Although I do have Kennedy sets, I do not collect varieties other than the 64 Acc Hair. But I will agree with you the FS106 is far more eye catching than the FS103.

ProofCollection

Yeah. I would advocate that the composites be modified to allow both FS-103 & 106, but I don't know if that's a reasonable thing to do or if it would upset people, or if I were to argue for it, what that basis would be other than the 106 is more interesting/desirable, but that's just my opinion.

WAYNEAS

The registry set
“Kennedy Half Dollars Complete Variety Set, Circulation Strikes and Proof (1964-Present)”
contains both the ‘66 SMS DDO FS-103 and the ‘66 SMS DDO FS-106 coins containing their own individual slots.

The FS-106 is the better looking coin.

Wayne