Line Flow - Generic, Bill Only with Inventory Interface

Hi,

For our counter sales we have two scenarios where first customer walks in and picks material from shelf for which i used workflow 'Line Flow - Generic, Bill Only with Inventory Interface' to enter a line.When i enter a line without Subinventory it was giving an error and got into Inventory Interface eligible activity. Once i entered Sub inventory and progressed it went ahead and interfaced with inventory and Receivables. Is this standard behaviour, please confirm.

For Second scenario where customer picks material at later time I followed steps in below note id but the moment i reserve material and book, line immediately interface with inventory and Receivable to depletes inventory and to create invoice.Is this standard behavior or iam doing some thing wrong. Please advise and suggest how to get line eligible for program "Inventory Interface - Non Ship" to pick at later point of time.