I feel for what you've been through azgrandma. I have experienced physical, mental and emotional abuse in my life. If something happened to my child in that persons care I would probably have my suspicions also. Unfortunately, I have known many women and men that have suffered abuse, but I don't know of any that have murdered their child.
I have to keep a open mind to all possibilities. It would do no good to put all eggs into one basket because if MR didn't have anything to do with Dylans disappearance, the real answers would never be found.
I do beleive that other possibilities are not being explored because as someone else said, sometimes it's just to painful to think about.
People are asking questions about Dylan to try and get a better understanding of him. I know it may look different to you as you read, because you are personally attached to the case. Knowing more about his personality can help to understand what may have happened. The time he spends with friends, he would be different than when he was just around his parents.
Is the family 100% convinced that MR did something to Dylan?