new Org Level impact in existing roles

Hi,

I would like to set/create 2 fields as organizational levels. For example KLART and DOKAR. Checking these I realized there is a big amount of roles "affected" by this change.

Because I plan to use the organizational level only for new roles , I would like to know which impact could have this change for existing roles, should one modify the existing roles after creating the Org Levels ? or in contrast they still work as always an no changes / adjustments is needed?

Thanks and regards

FedeX