B.C.
Saline is not addictive.
She IS thinking of nasal sprays like Afrin.
Saline is perfectly safe to rinse out the eyes, nose and sinuses as often as you want to or need to.
Any doctor will tell you it's one of the safest things you can use.
They RECOMMEND rinsing out snot/mucus with saline.
If she's open to it you might want to try to educate her.
If she's not open to it, try hard not to laugh at her out loud.
Just tell her to ask her doctor.