Although I truly am sympathetic to your plight here and personally support the idea for yo and the cildren, I think that you would be inviolation of your parenting plan with your ex wife and her right to make this decision long with you for the benefit  - or not a she shees it - of the children.  And I could see her hauling you back in to court in violation of the agreement and I think that you could ideed be held acountable by a judge.  I do think that your older daughter is approaching an age where the court would take her wants i to consideration should they be articulated in a logical and intelligent way.  But I think that you would have to ask the court's permission here.  Good luck.