How do I set search results of To (Participants) Email Address when users send Email with Relationsh

Currently, search is looking for matching e-mails/names from contact and user object for the current account on which CTA is created.

Is there a way or can we have this search narrowed down at Relationship level if we add contacts at relationship level. Because relationship contact object has a look up to contact object.So we should be able to add relationship filter.

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