You can do what’s called a Rider Swap. If the child is tall enough to ride, all 3 of you need to have the VQ. Talk to the CM at the entrance to confirm, but most likely you’ll all go through the line together, then one of you will ride while the other parent waits with the child in a designated area near the boarding dock. When first parent disembarks, you’ll swap so the second parent rides while the child and first parent leave (to meet up outside).
An alternative is for only the parents to get VQ. Once your VQ group is called, you can ride any time - there’s no deadline. So when your VQ is called, parent 1 goes to ride while parent 2 and child do something else. After riding, parent 1 meets them and takes the child while parent 2 rides. The child can’t enter the line without a VQ, if they’re tall enough to ride but simply don’t want to.