balcony relief area

I am taking a 2-day / 2-night trip and a trusted auntie will come stay with my dog, at home, to keep her company, feed and administer meds. since she's inexperienced in walks, our regular dog walker will come 3 times a day to take doggo out. thing is, there's a 14-hour gap of time between last walk at night and first walk in the morning due to the dog walker's schedule. my girl is a champ and can hold it, but i don't want to put her in that position and cause her needless discomfort.

so i'm again trying to set up an astro turf situation on the balcony where she can be let out and relieve herself for a quickie either before bedtime or first thing in the morning. she's not having it. i had tried this before when we had massive snowfall and she was struggling to pee outside because the snow was burning her paws. didn't work then, either. this time around i've taken the astro turf to the yard and stomped on it so it would "absorb" outside smells. i've also slid it under her when she's doing her business so she has peed on it 4 times and pooped on it as well. i brought the turf home and placed it on the balcony but she's not interested. i lead her to it on her leash and give the "go potty" command with treat in my pocket, which of course she smells and she just sits waiting for the treat LOL

any tips how i can get her to recognize this is a new spot where she's allowed to pee? forgot to mention i also sprayed those toilet training sprays on it. for reference, she's about 15-lbs, approx. 9 years old and refuses to potty anywhere but outside. preference is grass.

thanks in advance.