Your idea is met with skepticism. "I don't know..."

So you add "She is a mage. She should be able to do some useful things for you. And you can always eliminate her later."

There is some debate, but finally your idea is accepted. "All right, cough her up, Lizzy, and we will enroll her as a slave."

Lizzy complies, after warning "I caught her, so I get to digest her." a claim the others accept.
Turning to the spit out Failiel, Alexandra offers her a vial "Drink it. Once you are digested, you will reform here and will do as we order. You are now our slave and property and ours to do with as we please."

Failiel is not immediately compliant. "You can't do this to me."

"We are doing it and your only option is how rough we are going to be about it."

"Please, I beg you..." But hoping for sympathy from vores is a weak hope indeed. They have consumed hundreds and see no reason why food should get sympathy. Indeed... "Failiel, you have annoyed us for far too long. Drink and become a slave, or we will find other ways to pay you back which you will like even less."

Failiel blubbers for a bit, but eventually realizes she has no choice and drinks the vial. "Good, now get your head between my legs and give me reason to think you worth keeping around as a slave."

Failiel objects "But I've never ... done that."

Alexandra grumbles "I never did like amateurs. Well, you two have a weakness for them. Who wants to break her in?