Good to see the age and the fact that a formal diagnosis has been undertaken. Given the avoidance issue, this is a learned response, one that is deeply imbedded in the individual. At 35 they have a long and deep history that needs to be addresses and or modified/changed. Not a easy task for them or their family! So you will need to work day-to-day with this person to redirect and rebuild them
A "body double" is one way to achieve this ... it's simplify a individual who regularly checks in with the person and sees want's on the plate and helps them move it forward. This could be a family member of a paid professional ( with ADD experience). Good luck.