Possibility of injecting custom header in every Webhook event that originates from a store

Hi there,

I’m building a Public Shopify App, that I want to get listed on Shopify App store.

What I want to know, if there is a possibility using which I can inject a custom field within the headers of any Webhook originating from a store that would install my app. Ideally, I want to provide a UI on the app, where the store admin can enter a custom token that my service would provide to the store owner. An whenever a Webhook originates from that particular store, I receive the same token either in headers or somewhere in the Webhook body, using which I can authenticate back the Webhook call received in my service.

Also is it possible to have this parameter different on the basis of stores that would install my app?
Thanks