Performance Period Extension, Post-Reviewer's Comments

Hi All, I am working on a project that has received it's initial reviewer comments. We are working on updating the credits that were pending however, some credits require new work (additional alternative transportation survey, etc.) This will affect the performance period date of these credits as they will need to be extended to include the new surveys/ information. Does this mean that now all performance period dates for all applicable credits need to be extended, or can we just update the pending credits and leave the initial performance period as is? We are nowhere near the 24 month maximum, so there is plenty of room there. Thanks!