Two networks, overlapping CIDRs, no cutover weekend.
Peering needs non-overlapping CIDRs — an acquired company's VPC almost never has one.
Immediate bridgePrivateLink connects only the services that must talk now — no re-architecture, no CIDR requirement
Longer-term projectRe-IP one side onto non-overlapping ranges
Full integrationOnce re-IP'd, a clean Transit Gateway connection becomes possible
A real M&A integration is staged over months, not solved with one clean mechanism on a single cutover night.