My parents married in 1968, my dad retired from teaching in…

My parents married in 1968, my dad retired from teaching in 1998 at which point he started receiving his pension, my mother never worked for pay, my parents separated in 2000, and my dad started collecting CPP in 2007 at age 65 (at which point the first pension reduced by an amount slightly less than the CPP amount). They both remarried and live in (and have always lived) in Ontario. Their separation agreement in 2000 said something to the effect that "Because he is receiving an annual income of approximately $40,000 per year, Husband will pay Wife regular support in the amount of $1,800 per month, in effect June 1, 2000." My dad's defined benefits pension plan from the Ontario Teachers Pension Plan and his future CPP were not mentioned explicitly in the separation agreement at all, although presumably "he is receiving an annual income of $40,000" implicitly refers to these pension assets. All other assets were divided fairly. The separation agreement was drafted by my dad's lawyer and signed by my parents at the local courthouse; my mom had a legal aid representing her with whom she spoke on the phone before going to the courthouse for signing (without a penny to her name she couldn't afford a lawyer). I feel that the Teachers Pension should be split approximately 45% to my mom and 55% to my dad, given the percentage of my dad's teaching career they were together. Noting that the pension plans are indexed to inflation, I calculate that she has received over $30,000 less than that to which she was entitled these past eleven years. My question is this: Given that my dad refuses to register the separation agreement with the OTPP, continuing to write monthly cheques to my mom in the amount of $1,500 apiece, could I contest the separation agreement and somehow secure an equitable division of the Teacher's Pension for her? (She has already applied for credit-splitting of the CPP which doesn't recognize separation agreements in Ontario. Also note that she won't initiate a legal action -- it would have to be me initiating the action on her behalf.) I am thinking that the separation agreement is not as explicit as it should be to weather legal action -- "support" seems to be referring to spousal aupport, another matter entirely, and the pensions are never explicitly mentioned, meaning that the nature of their division is yet to be decided. Or is it in fact binding, end of story? Thank you.