CRM - Billing plan

Hi,

We are planning to use Milestone Billing . However our leading system is CRM. When I read thro some of the SAP help doc.

It says CRM billing plan order can't be used in ERP. What I understand from this even tho CRM billling plan functionality is avilable we can't

create Sales order with Mile stone billing in CRM and replicate to ECC for processing it for down payment with billing type FAZ.

We are using ECC for our billing , we don't use CRM for our billing.

Could some advice what should be the best desing approach.

Thanks & Br

mathi