My daughter was first diagnosed as bi-polar in 2003, then as paranoid-schizophrenic. She is now homeless somewhere in the States.

I continued to pay her loans for her since 2003 until now hoping she might get better, but I don’t see that happening, and there is still over $4000 balance.

I am not legally responsible for this bill, and I would like to know what the consequences would be to my daughter in the long run if I stop payments, as I am now retired and find the payments difficult.

Thank you for your advice.

Depending on where you live, if and since you started paying them, there may be some assumption of your liability to pay. ** you would have been much better off not paying on them.
But assuming they don't go after you,

They sue your daughter, get a judgement, and if she ever gets a bank account they can take the money, or if she ever gets a job they can garnish her wages.

Thank you so much. I thought as much, but was hoping I was wrong. Thanks for taking the time.

... since you started paying them, there may be some assumption of your liability to pay. ...

I suppose there may be some authority for that somewhere, but in the great majority of jurisdictions, the daughter's creditors would not be able to successfully sue the mother under those circumstances.

Thank you, that is good to know.