Stranded

I have ADHD.  I was never evaluated or treated as a child.  I have an adult daughter with ADHD who refused her medication as a child.  She is now a felon with a drug problem.  Her oldest son has been (sloppily) diagnosed with ADHD and his doctor recently increased his medication because he gained three pounds.  I say he was sloppily diagnosed because I am willing to bet that no QEEG or PET or SPECT scan was done. This statement is made based on the area we live in.  He has never been evaluated for other possible neurological disorders.  He has lived most of his life with me, and I am the family member who knows him best, and has been more involved with his activities than any other family member, including his parents.  He and his brother are currently "living" with their dad who lives with his grandparents.  Dad is rarely home and great-grandmother has the bulk of the responsibility for both the boys.  I am not convinced my grandson has ADHD, but he is very depressed.  How can I help him?  I am not afraid to talk with his dad, but need some idea of what to talk about!