Move from one benefit program to another during open enrollment

Hi Team,

We have 2 benefits program currently and set of employees will move from one benefit program to another benefit program but not all. we are looking to show defaults from current selection and map it to equivalent plan in the new program as default plan and options in new program. 

So, We are thinking to attach Fast formula to open enrollment life event process to see the default enrollments are pulled as coded in the FF. Please let us know if this approach will work fine or Any better approach than this?

Thanks.