Looks like she is really pushing her “luck” here. (pun intended) You do know 77 is the Gematria for Mazal, wink, wink, so whose luck is she trying to change, the cat, hers, or yours?? Because after 77, either, you will end up hating the cat or will never want to part from it.
Cats(and all animals) are a responsibility. Are you prepared for the vet bills. Are you getting it already altered? Because halachically you may not alter an animal. You can obtain one already altered from a shelter like Bideawee. It would be irresponsible to bring a cat in and her have kittens. There are already too many. And trust that shelters do not need anymore. They will euthanize any cat brought to them, even if it sneezes. Cats have a need to scratch things. Male cats will spray to mark their terroritory. Then there is the litter box to clean up. Making sure to feed the animal before yourselves, Not touching an animal on Shabbos. davening with the animal in the room.