I'm pretty sure someone has talked about this already, but I wanted your guys' opinion on this, and it's been on my mind for a while.
So there's the spoken echoes at the Minor Erdtree Church, where she says:
"I declare mine intent, to search the depths of the Golden Order. Through understanding of the proper way, our faith, our grace, is increased. Those blissful early days of blind belief are long past. My comrades; why must ye falter?"
This is the clearest direct statement that Marika had moved past blindly believing in the Order she helped create and was actually questioning it.
O Radagon, leal hound of the Golden Order. Thou'rt yet to become me. Thou'rt yet to become a god. Let us be shattered, both. Mine other self.
Here, she of course orders the shattering of the Elden ring, and is the ultimate act of rebellion against the greater will.
"The assassins that carried out the deeds of the Night of the Black Knives were all women, and rumored to be Numen who had close ties with Marika herself"
This isn't a clear statement that Marika also took part in orchestrating the event, but it's a strong implication that she may have. Ranni claims to have did all of it by herself, but could a young Ranni really steal a fragment of the rune of death guarded my Maliketh himself, when his whole purpose was guarding it? Not to mention the theft was called Marika's betrayal of Maliketh for some reason. Then there's what the Finger Reader Crone in the Deeproot Depths says:
"Ohh... Oh, Lord Godwyn... Such cruelty, such humiliation... My poor, sweet lordling should have died a true death. As the first of the demigods to die. As a martyr to Destined Death. But why must it yet bring such disgrace? A scion of the golden bough, sentenced to live in Death..."
After growing tired of the Greater Will, perhaps she needed a reason to keep her plans of ending the Order. What better proof and reason would there be than the Golden Boy of the Order somehow dying? But dying a true death, actually passing. And instead, I believe that's where Ranni twists the plan around for slaying only his soul. Also, I don't really see a reason for Godwyn specifically to be killed, Ranni didn't really have much reason to care whether she pisses off Marika, she just wanted to sever the ties with the two fingers. This is why she may have been driven to the brink. Obviously someone who first orchestrates the death of their child wouldn't mourn them after, but that may not have been the case if she wanted him to die in some kind of sacrifice to bring death back to the world, a "martyr to Destined Death". She already didn't care much for her children, and we can see that in another one of Marika's spoken echoes:
"Hear me, Demigods. My children beloved. Make of thyselves that which ye desire. Be it a Lord. Be it a God. But should ye fail to become aught at all, ye will be forsaken. Amounting only to sacrifices..."
She calls them children beloved and then tells them they will be abandoned if they don't become something useful. It's either succeed or be discarded.
But that's just my thought on this, obviously I may be wrong and be disproven, but I felt like it's something I could share.