Cousins might be bad influence

[Anonymous]

My SIL is a very nice person but we have very different values. Her daughter is unfortunately a year older than my DC. They spend a couple of weeks together each year with inlaws who have values similiar to ours but are blind when it comes to cousin. Now that cousin is getting to be a teen, I worry that cousin will negatively influence my DCs. SIL hangs out with the partiers (still) and was involved in drugs when she was younger. Cousin seems to have developed a slight attitude and values don't reflect ours. My DCs read for fun...hers doesn't like books. Hers thinks there is nothing to do at inlaws, mine enjoy the time. My oldest DC loves her cousin and looks forward to spending time with her as they get older I worry about the time they spend together. I would prefer if my kids were with my inlaws by themselves but if I said something it would be horrible from a family dynamic situation. We are not there yet but if things continue on this path we might get there. How do we avoid getting there? Is there anything we can do?