Profit center

My question :

At the time of sap implementation, there is only one manufacting plant and one profit center, as time passed, 2nd manufacturing plant at different state, has been opened and start production too with the 1st company profit center only ( like purchase order created in the address of new manufacturing plant but billing is done by 1st manufacturing plant, which gives not a clear picture of accounts ... Now company wants to check accounts / reporting with different profit center. What should I do first and what precautions I have to make before doing this and what will happen of those transactions, of new manufacturing plants with 1st profit center. All of sum, company wants different profit centers for different locations for reporting purpose. Please help.