Can I amend to add a form of payment?

[ERISA-Bubs]

Say I have a Nonqualified Deferred Compensation ("NQDC") Plan that allows only for lump sums or installments over 10 years. I would like to add by amendment, effective 1/1/2014, that allows participants to also chose 5 year installments.

Can I allow an employee to make a subsequent election whereby he changes a 2008 election (deferring 2008 compensation) from a lump sum to the new 5 year installment option?

Of course, I would apply the subsequent election rule -- the election isn't effective for 12 months and delays the initial payment by 5 years. But can I allow him to change to an option that wasn't around when the money was originally deferred?