Feature Request: Control Over New Texture Channel Activation

When painting textures, there are situations where I need to add a new channel (for example, Opacity) at a later stage. Currently, when a new channel is added, it is automatically enabled for all previously used materials, even if I do not want those materials to use this channel.

I would like to have control over how new channels are applied to existing materials. Specifically:

• An option to automatically enable the new channel for all existing materials, or
• Have the new channel disabled by default for existing materials and allow the user to manually enable it per material.

This could be implemented as:

• A confirmation dialog when adding a new channel, or
• A project-level preference that defines the default behavior.

This would prevent unintended changes to already finished textures and improve workflow flexibility.