Unfortunately, you can not deduct expenses unless you are legally obligated to pay them. You can not deduct your daughters property taxes unless you are on title to her house. To deduct any tax, there are two requirements, 1, the tax must be imposed on you. If you are not on title to the house the tax is not imposed on your and you can not deduct it. You can not deduct the mortgage interest on her house unless you are legally obligated to pay it. If you are not a signer of the mortgage, then you are not legally obligated to pay it and you can not deduct it. Your daughter's situation is not relevant.
