What does it involve to get a guardianship dissolved ?

My parents have guardianship of my 3 (almost 4) year old son and 3rd party custody (which I am still confused about the difference and reasoning for this) of my almost 11 year old daughter. This was the outcome of a CHINS case that lasted almost 3 years in total. The final result was the guardianship agreement. The chins case was opened for drug use and I Tested negative to all my drug tests during this time (except one for benzodiazepine). My children have been in my physical custody since around march of 2020, which is when the guardianships were finalized for the children. I have since continued sobriety and now have a 3rd child who is 8 months old and everyone is doing great and are safe and taken care of. My parents are in agreeance with the dissolution; what are the chances I have of a dissolution actually happening ?