C.E.
do you have a friend in a similar situation who would swap babysitting with you for free? you watch her kids a few days a week and she watches yours a few days. i find that my kids often behave better with other kids in the house because they're too occupied to pick on eachother. i haven't tried it on a long-term basis, though. maybe once they got used to seeing eachother a lot they would start to fight like siblings, i don't know. but anyway, it might be a good solution for you. also there are many daycares that also offer preschool during part of the day.