Contact transfer

Contact transfer

How to transfer the contacts to another company, but maintain old logs.

lets say Mr. John is with M/s XYZ and we have few opportunities with him and eventually he joins a new company M/s ABC. I need to add Mr. John in M/s ABC.

01. Should i delete Mr. John in M/s XYZ?
02. Add Mr. John in M/s ABC?

how to handle this.

Regards