Rigidbody help

Hi I have a rigidbody trigger. It has a box collider child right below it. When my character controller enters the rigidbody trigger he becomes its child. The box collider child under the rigidbody trigger is what my character controller walks on. I then have another trigger box under all of them. This second trigger box has a script using addforce on the rigidbody trigger. I'm doing all this to simulate a boat moving up and down on the waves. The problem I am encountering is that sometimes I'll get a bug where we all fall through when my character jumps. It only happens sometimes. Also my character is supposed to unchild from the rigidbody trigger upon exit and sometimes when I jump I notice I am still the rigidbody triggers child.