custom ATP Check

Hello All

We have custom ATP(Material Check) functionality built in ECC. And we are in position to use this custom FM to carrier out ATP in CRM and show some additional information on the Order.

Please advice on the following:

1. Should we have disable the standard ATP configuration in CRM since we have a custom logic built in ECC

2. Is their any BADI available for carrying custom ATP check(regardless of Configuration) and bring additional data from ECC?

3. How can we use standard fields that holds Confirmed Quantity and date to hold the same data but from custom ATP FM

Cheers

RJ