ACA Reporting - check ACA Fulltime box for enrolled PT employees?

Our medical plans are offered to employees who work 20-29 a week.  They are not ACA Fulltime but because our medical plans are self-insured, their enrollment should be reported.   Do we need to check off the ACA Fulltime box on those PT employees enrolled in the medical plans or will the self-insured designation on the plans capture those enrolled?   This question would also apply to our retiree base as well.  Thanks for your feedback!