Last week the DOL announced that it was issuing new optional FMLA forms. You can find the announcement, and the forms, here. https://www.dol.gov/agencies/whd/fmla/forms
The new forms contain some subtle differences and, as I said, they are optional.
As always, keep in mind that you cannot require an employee who has already provided you with certification documentation to fill out the new forms nor can you even require an employee to use any certain forms. Per the DOL: “An employer must accept a complete and sufficient certification, regardless of the format. The employer cannot reject a certification that contains all the information needed to determine if the leave is FMLA-qualifying.”