If one party only is "reconciled" to another party, whatever is going on between them is not reconciliation.
If all are reconciled, Paul would be silly at best to call on others to be reconciled. If we become reconciled when we trust than we are not reconciled until we trust and not all are reconciled.
A full reconciliation occurs when both parties agree to be reconciled. This is why Paul said, "Be reconciled to God" 2 Corinthians 5:20.
It is possible for one party to be reconciled to the another party without their consent.
"God was in Christ reconciling the world unto himself" 2 Corinthians 5:19.