Hello !
It is possible to complete your flow in POS but it required some customization.
We can discuss somewhere to know your complete requirement.
You can look at our blog sites.
We have developed many features in OpenERP Point of Sale.
http://acespritechblog.wordpress.com/2013/05/01/create-invoice-from-openerp-7-0-point-of-sale-pos/
We have also created sales order report directly from Point of Sale.
Thanks,
Acespritech Solutions Pvt. Ltd.
www.acespritech.com
Mail: info@acespritech.com
Skype: acespritech
Gtalk: acespritech
Blog: acespritechblog.wordpress.com