Mid-Year Administrative Event to Add New Benefit Plan

Summary

Mid-Year Scheduled Administrative Life Event needed to add new plan, but not impact existing enrollments.

Content

I need some assistance.  I need to add a mid-year Scheduled Administrative Life Event to all benefit eligible employees as of the beginning of our fiscal year to add a new benefit plan to everyone's record.  I am having trouble creating an event that will add the new plan to everyone's record without wiping out the HSA and FSA elections made during OE and any other changes that employees may have made.  Can anyone give me some advice on how to configure the Administrative event without causing issues for existing enrollments?