If the grandparents are generally over-anxious and easily alarmed people, it may be worth one (1) conversation with them (and as previous commenters have pointed out, it shouldn't just fall on the women involved to facilitate this) along the lines of "blah blah developmentally, blah blah she's TEN she'll be going to Big School* soon, blah blah importance of taking manageable risks". Addressing it from that point of view is likely to go down better than a "back the fuck off and let me raise my own kids" (though keep that as a nuclear option if you want). I also really agree on letting the kids stand up for themselves here. Like taking their own risks, learning to stand up for themselves is something you should be teaching them. * depending on your location