Our cohort has been followed-up from the subject's birth for over 40 years now. We have multiple evaluations of the socio-economic status of the subject's parents from the time when the subjects were newborn, 5 years, 9 years, and 16 years old. Obviously, the parent's SES has improved over time in many cases. Do you have any suggestions how to handle this now, when we are analyzing 40 year data of variables that may be affected by the childhood SES?

Edit: Added three question topics.