English teacher/helper

#1
We are looking for an English teacher for our children, both of whom are fully bilingual, so this is not the standard EFL situation. Our kids are twins, age 9, lived in the US though kindergarten when we moved to Spain, where we lived until now. They are in third grade here in BA, only attending school in the mornings since we decided against enrolling them in the afternoon English classes offered at school. What we want is a tutor to help with the aspects of schooling that they've missed out on in English (basically, spelling and grammar); reading has not been a problem for them. If there's anyone out there with a primary education background, we would love to talk to you about tutoring and perhaps helping out picking them up from school once or twice a week. Preferably, someone who plans on being here for at least the rest of this year! Thanks--Sarah