identifying triger point & stoping an idoc from getting generated in SD

We have 2 boxes

KLE 420 ( CRM box) & KLE 430 ( SC box)

As per original business flow

1) Sales order is generated in 420 ( order type Z001, item category ZAN1 )

2) idoc is generated and message/details is transferred to 430 ( Z002, ZAN2 )

3) in 430 the delivery & shipment is created and idoc is generated and transferred back to 420 where the invoicing happens.

As per new flow

For some selected orders, the initiation(SO) and processing needs to be completed in 430 (SC) only

When I run an order cycle, a few things I need to know is

1) how do I identify for which steps in the order cycle, an idoc is being generated

2) how can I stop this Idoc from being generated ?