Hello, my name is Dr. Kara and I have over 20 years of experience as a veterinarian.
I understand that it would be nice not to have to clean a litter box but this may be something that Basil needs and wants at 9 years of age.
When she was at your old place she was comfortable and secure. She was used to eliminating outdoors and she felt it was her territory so she was comfortable going outdoors.
Now that she is a bit older and you have moved to a new place she may feel intimidated by smells and sounds of different wildlife and cats and dogs in his new neighborhood. Animals use eliminations as a way to mark territory and she may not feel confident enough to do that at your new place. She may feel the litter box in the house is the only truly secure place for her to eliminate, and she may panic when you try to take it away. I know that initially she was eliminating outdoors but perhaps she was challenged by a neighborhood cat marking over where she went or was chased or scared when eliminating outdoors which has now changed her perspective.
You can try putting some of her waste from her litter box in an area where you would like her to go outdoors, that way it will smell like her and may make her feel confident enough to go there.
You do want to clean any of the areas that she has gone indoors thoroughly with a cleaner that has enzymes, such as Nature's Miracle. If any odor is left she will be drawn to eliminate in that area again.
You can also try putting a pheromone collar on her to reduce her anxiety enough that she may try eliminating outdoors again. Here is a link to some examples:
Best of luck with your girl. Please let me know if you have any further questions.