Sale and Purchase between two exciasable plants under single company code

Hi Experts,

Please suggest solution with necessary steps for the below requirement,

• >  Sale and purchase scenario between two excisable plants under single company code.

• >  Suppose say, one excisable plant is in Delhi and another excisable plant is in kolkata.

• >  Please Note that  Currently we are using STO process, instead we are going for sale and purchase   process.

Thanks in advance,

Mahen.