It gets tricky when you're dealing with "managed by" profiles under someone else's account. If you weren't connected as friends before, it's quite possible that your kids now exist twice as "managed by" profiles. Once under your account from a previous trip, and again on your SIL's from when she booked the trip.
If she wasn't already connected to you and your kids as friends, then by entering their (and possibly your) names in the reservation she created duplicate versions of you under her account.
The best bet is to do this:
-Under the "you" in *her* profile, have her invite you to be friends using your email.
-Once you accept, she should then friend request your kids using the "mutual friends/friends of friends" feature. (Make sure you are allowing your friends to be seen)
-At this point, she will likely have two versions of your kids. She needs to go into the reservation and change it from *her* version of the kids to *your* version of the kids.
-After you confirm that you and your kids are linked to the reservation, she can then delete the duplicate versions of them, leaving just the ones that are controlled by you.
If you can't do all of that, unfortunately it will require a call to the MDE Help Desk.
And all this goes back to my #1 tip regarding My Disney Experience: take the time to set up profiles and link everyone as friends BEFORE you book anything. A few minutes spent up front avoids hours of headaches down the road.
-Rob