Just heard from my niece in law that she has 2 red sex linked hens that are also broody. I have been inundated with Wyandotte broodies over the last 3 years, but sex linked?
There are two different types of red sex links. One is the commercial egg laying hybrids. These have relatively small bodies, leghorn sized, and lay a lot of large eggs. They are bred to not go broody often. You can never totally breed broodiness out of a flock of chickens but you can make it very unlikely they ever go broody.
The other type is when you cross a rooster pure for the gold gene with a hen that has silver. Many hatcheries sell this type of red sex links. Since they are typically crosses of dual purpose chickens the offspring have the same general characteristics as their parents. Not close to the commercial hybrids.
What are they doing with these chickens?
Generally nothing that different than they have been doing for decades. It helps to know which type of red sex link you are dealing with so you know what to expect.
One possible difference is that in the last few years hatcheries have been using different dual purpose breeds to make their red sex links and giving them cute names as a marketing ploy. In the past most hatcheries used Rhode Island Reds or New Hampshire as the rooster with gold genes but now they could be using other breeds. The hens with silver they use have been changing too. The breeds they used to use generally don't go broody that often but if you get one of those new crosses maybe they do go broody more often. But these are not likely to be called Golden Comets.
We settled with Golden Comets because of their laying ablities and rarely go broody.
If you know which hatchery they came from we may be able to tell you which type of Golden Comets these are, commercial hybrid or a cross of two dual purpose breeds. Golden Comets are not a breed, it's just a marketing name.
What else can i do to get my girls to quit?
The way I break a broody is to put her in an elevated wire-bottomed cage for 72 hours. The air hitting her underside seems to help break her form being broody. This keeps her away from her nest so she doesn't get any reinforcement. I put food, water, and nothing else in there. It needs to be predator safe and not somewhere it becomes an oven. If 72 hours isn't enough I repeat.
I'll repeat this. You can never totally breed going broody out of chickens. Just like not every chicken of a certain breed will go broody. You can breed them so whether going broody or not going broody is highly likely.