Hello
She sounds like a busy determined digger! Is she a Syrian? They do sometimes like an ensuite bathroom and I find if you give them a large house they move their pee corner inside the house, away from the nest. So I have a large house with a litter tray inside.
What I would suggest is popping a new house over her current nest next to her litter tray. eg a shoebox house. Which is large enough to contain both.
Cut the base out of a shoe box and keep the lid as a lift off roof. Cut a hole for a door in one of the long sides, near one end. The end with the door is the corner where the litter tray needs to go, at the back. Just pop it over her nest and litter tray so that the litter tray is at the door end at the back. Putting a bendy stick bridge over the door makes it dark inside, which they like, and also gives a ramp up to the roof so you can use that to put a food bowl on (so she can't dig under it!).
I am sure she will like that arrangement. Assuming the litter tray isn't too large! You can buy one that will fit in a house. Rodipet make ceramic corner ones. You can then use the lift off roof to empty the litter tray when needed, so you don't needto remove the house and the nest fall apart etc.
https://www.rodipet.co.uk/accessorie...rt-size-m.html
I actually have this house for our hammy - it needs a big cage to fit in! And he uses the litter tray inside it in one of the compartments.
https://www.rodipet.co.uk/houses/rod...erracotta.html