Refetching data in multiple parts of the code at the same time

My problem is : I have a component named HeaderComponent with some props coming from graphql.
This component is used in two pages of my app.

In the HeaderComponent in page (1), I modify one of the props by doing a mutation. Then I refetch the new data.
In the HeaderComponent in page (2), I want to have the new data that was modify in page (1)

How can I do that ?

Because I try some stuffs but it didn't work.
Thanks !

The issue only identifies a HeaderComponent shared by two pages and a GraphQL mutation/refetch; no repository file, test, or entry point is named. Start by reproducing the two-page data flow and consulting Relay's store and refetch documentation; done would require a clarified, reproducible behavior and an agreed code or documentation change.

Written by the indexing model from the issue text.