Old RRSP overcontribution

Client retired in 2010, received an eligible retiring allowance. Transferred to an RRSP. 2010 return , not by me, didn’t claim the transfer, left her with an overpayment. That was partly used up in 2011. She hasn’t generated RSP room since then.
I’d like to amend her 2010 return to leave her with only the amount unused that was claimed in 2011. But, we’re way past the 3 years. Fairness app?