Sir Edward de Warren, Knight - Who is Cecily de Eton's husband?

John Parker Earwaker shows in his chart (attached) that Cecily was married to Edwards brother William. Both were illegitimate sons of John de Warren and Maude de Nerford.

Earwaker's chart states that William and Cecily would have been married in 1340, while Edward was in France. Are there other contemporary sources for the marriage to resolve this issue?