How to calculate the distribution level cost allocation % or amount in POR_CUSTOM_PKG

Hi, We have customized the por_custom_pkg to validate the charge account entered in the charge accounts tab at distribution level and is working fine if there is one distribution. We now have a requirement to further add some more validations whenever the cost is allocated to multiple accounts using the 'Split' button depending on the allocated amount to the account. Checked and could not find any parameter referring to allocation% or allocation value in CUSTOM_VALIDATE_REQ_DIST procedure. Request your help on this.