for the most part I do suggest to keep all business relationships, business. However over the past 10 years I have met a few families that have become more than just business, even then...it involves only the children. I have been invited to their home by the Mother for a girls night before, and I politely declined, she did ask one more time and after my second decline I think she got the picture. I don't think it is a good idea to develope such a "tight" relationship between adults but the kids will always have the opportunity to develope freindships which are for the most part quite harmless. My children and I have been invited to most of my Day Care Kids Birthday Parties and we always go! My children are invited as "friends" (of course) and I as "day care provider".....the kids are always thrilled to see us arrive and I wouldn't miss it for the world.
IMO. You may tread on thin ice becoming friends with Day Care Moms and Dads....most times business doesn't mesh so well with pleasure. Having you're children be friends is nothing deeper than your child going over to play with a friend from school.....you are polite to one another at pick up and share conversation but nothing much deeper than the kids.