Manage multiple audiences

We need to consolidate contacts before the quarterly outreach. Merge duplicates across our three audiences: Leads, Customers, and Newsletter. Keep the Customers record as authoritative when conflicts exist, preserve purchase history, and remove the old Leads tags. After merging, export the new consolidated audience and retain only one contact per email. Complete this before Friday's send.

Before I merge our multiple audiences, make it easy for the CRM lead to approve: list how duplicates will be detected (email exact match plus phone fallback), show which audience wins on conflicts (Customers), explain what data fields will be preserved or discarded, and flag any automation triggers tied to each audience that will break when contacts move.

I started consolidating Leads, Customers and Newsletter lists and the system shows dozens of automation workflows attached to the Newsletter audience that will no longer map after merge. I can't tell which workflows are still needed. What is the fastest way to decide which automations to keep, how to test them with the merged records, and the minimal rollback if something breaks before Friday's send?

Every quarter I consolidate audiences and then engagement drops because automations, suppression lists and personalized fields get mangled. I run the merges and the ops team says it's the fastest way. What recurring mistake am I making—too-frequent merges, no ownership of segmentation rules, or failing to version automations? Recommend one habit to change now and one process to lock in so future merges don't kill deliverability or personalization.