Is it beneficial to get put on a line of credit that has been open for at least 10 years? I have read a few places that if you get your name on a credit account, then you will assume all of the accounts history on your credit score.

this would be good for establishing a credit history, unless you were to abuse it and damage your parents credit as well. I am considering doing this, and not even having my parents give me the card. That way, they would still be spending the money, and i would get the history. Its a risk for them, but it could pay off for me if done right.

The big question is whether they will report it as your credit line. It's not always the case. Sometimes it's easy to add co-signers without any kind of repercussions - for example, I was once able to get my dad a card by adding him as a second account holder without ever giving the bank his SSN. Obviously, such "addition" had no effect on his credit history.

personally, i would suggest talking to the issuer (is it a bank?) and asking them directly.