No one can seem to come up with a proven answer. 

What we DO know, is that merle cockers are here, have been around awhile and will probably be around for some time to come. 
The merle cocker isn't just a puppy mill, creative color breeder, or back-yard breeder concoction anymore. 

Merle is in most lines and all varieties of cockers. 

Breeders are breeding their merles to champions and champion lined dogs. 
Many Show breeders are ignoring the issue as they feel they don't have to worry about merle showing up in the pedigrees. 
These people are very wrong. All it takes is someone to breed a merle to a show dog and you will have merles.
People who breed show roans are getting worried as some breeders, INCLUDING BREED AKC JUDGES cannot tell the difference between a merle and a roan. 
Already instances have come up where a show home purchased what they thought was a nice roan for show, only to find out it was actually a merle. 

Whether we like the merles or not, they are here and in our pedigrees.

What we ABSOLUTELY HAVE to do, is to demand that these merles are listed with AKC AS MERLES!
Contact the parent club, and GET THEIR ATTENTION! This is not a political issue or a color issue. 
This is a HEALTH issue! Cockers already have enough genetic health problems in the lines without accidentally breeding 2 merles together and adding a LETHAL gene to it. If the merle gets into inexperienced/unknowing hands, you not only have the lethal gene to deal with but the plethora of other heath issues as well. 
This is an ISSUE that The American Spaniel Club MUST NOT STICK THEIR HEADS IN THE SAND ABOUT!! 
The ASC has been already contacted about this issue and THIS IS THEIR REPLY . 

We HAVE to get the merle listed with AKC as a merle, and not a roan! 
The Doberman Club through Patti Strand  created a Z-List  on their white dobermans. The procedure is to have the z placed after the registration number of offspring of the dog and any dog that is white. 
This lets breeders know that this is a white dog or offspring from it. 
We can do this with merles until AKC can list the dog as a merle. 
(Click on Z-List to find out more about this way of registering) 

But whatever we do, it needs to be done NOW.

I think the issue isn't where the merle gene came from, but more importantly where it's going. 

 The fact is merle's are here and have been for many generations.  They are registered with AKC as purebred cockers spaniels.  By now, after this many generations of breeding, they actually are purebred cocker spaniels, no matter the origin.  Whether you and others like it or not, when bred they breed true.  The only problem that we can address is how they are registered.  They are being registered often as roans, which most decidedly they are not, and that is what we need to remedy.  Arguing about where they came from is beating a dead horse and wasting time, in my opinion.  It doesn't matter anymore.  A dollar short and a day late kind of thing.

The merle gene can be lethal if not bred carefully and correctly.  There are definite defects linked to this gene in other breeds if doubled up on.  Eventually, we will destroy our roans if this matter is not attended to immediately.  Our parent club has decided to turn it's head and pretend there is no issue here because they do not believe they are purebred.  Hogwash  and bullcorn, I say.  Merles are here. Face reality.  It is the responsibility of the American Spaniel Club to see that they are properly registered, so that they can be readily identified by responsible breeders and not confused with our roans.

The breeders who do happen to believe in the merles, would be happy to see such an option.  They are proud of the merle and are not deliberately trying to hide behind another color.  Because of the narrow mindedness of the ASC, they are left no option except to register them as roans for the most part.  Breeders are often told, when trying to register their litters, (by AKC) to choose the color they most closely resemble and of course, that would usually be roan.

Whether or not merle breeders would ever push for the opportunity to show in conformation is surely unknown to me.  Because of the genetic problems associated with breeding merle to merle, I would personally not encourage such a thing and would vote against it should it ever come up.  But for the protection and purity of the 3 varieties we have now, they should be, at the least, properly registered.

SHOW YOU ARE CONCERNED FOR THE FUTURE OF YOUR BREED AND DO SOMETHING ABOUT IT.