Can a feedback questionnaire be added to an existing performance document?

My organization is currently doing Mid-Year Reviews which have been launched out to everyone. However, in the configuration we forgot to add the option for participant feedback/feedback questionnaire, so while feedback can be requested, participants are unable to see or complete the actual questionnaire.

I'm unable to add the feedback questionnaire in the Performance Templates > Document Periods tab under the "Questionnaires for the Period" section as the option is greyed out since the Mid-Year Review has already been launched. I also tried unchecking the box for Available to Use for the Mid-Year Review under the Document Periods section as well as trying to mark the whole performance template as Inactive.