yes, create the new reason codes, and new plan. Then use the Change Attendance Plan process I the left menu (not at the employee attendance summary level). Everyone one the plan will be change to the new plan as of the effective date you enter. If you only want to change a plan for a couple of people, add it at the Attendance Summary Screen and modify the old plan's effective dates. 

Thanks for the quick response.  I have another 100+ will stay in the old plan. Therefore I can't replace plan A with Plan B.  Any workaround for that?

there is no filter other than Employer level in the Change Attendance Plan Process. 

You can use the Add Attendance Plan and filter or use criteria table to add the new plan to the eligible employees, then manually end the effective date in their old plan. It will cut some of the manual effort but not all of it. You would create new reason codes, then the new plan, then Add Attendance Plans. this method will not let you assign taken to the new plan - you would have to manually adjust Time off transactions if necessary

I have all 200 employee's empno on an excel file.  Is there a way to change the plan using SQL?  Thanks again.

I see mass update under timeoff.  Will that work if I use expression builder to enter all empno?

I looked into that to see if you can update but it doesn't appear you can access the HATPLAN table 

any alternative?  I was hoping by using mass update to change plan ID code from one to another, it will take care of the plan A to Plan B transfer automatically.  Thanks.

you can make a copy of your LIVE to Sample Data and attempt. I have not been able to do it this way. I believe the plan code ID in mass update is for insurance or savings plans not attendance plans. 

I will give it a try.  Thanks.