How to handle Launchdarkly Feature Flags for existing c# Enum Feature Modification

I've been implementing Launchdarkly within a old .net framework webforms application. Things were going well until I came to this issue and I'm not sure the best method to mitigate it.

Problem:

I have an existing simple Enum and am adding a feature which added 1 element to the enum. The problem lies in the fact that the existing Enum which is already being referenced well over 100+ times throughout the application cannot contain the change unless the feature flag has been enabled for this new feature.

The biggest thing I need to take into consideration is I do not want to modify the 100+ referencing to isolate the feature change. I've thought about extracting the Enum and replicating it and directing the feature that uses it to a new Enum under feature flag situation but that wont work because the underlying use of if it will have impact outside of the feature.

Example:

public enum SystematicNumber
{
    Feature1,
    Feature2,
    Feature3,
    Feature4,
    Feature5,
    Feature6,
    Feature7,
    Feature8
}

Within this Enum Feature4 is being added but the feature is behind a feature flag and cannot exist until enabled.