I took over paying my mother's monthly PLUS loan payments, taken out for my education. (Sallie Mae autodeducts the monthly payments from my checking account.) Can I count the 1098-E for that account on my own returns, though the loan is technically under my mother's name?
No, you cannot. See the IRS instructions:
Generally, you can claim the deduction if all of the following requirements are met.
Your filing status is any filing status except married filing separately.
No one else is claiming an exemption for you on his or her tax return.
You are legally obligated to pay interest on a qualified student loan.
You paid interest on a qualified student loan.
You're not legally obligated to pay the interest, your mother is.
Your mother cannot claim it because she was not the one who paid the interest.