Marketpress / Multisite

I want to be able to do a manual order entry process for point of sale tracking done at our physical site. Most customers purchase online, but some purchase on site with cash. I want to have these orders all collected in MP for tracking purposes.
1) I want to enable manual orders but not for the general public.
2) Can I create a separate, private site using multisite that has manual purchase enabled. The marketpress iteration would post orders into my existing MP implementation so all orders would be in the same "store."
3) Alternatively, a simple manual add order option in the order manager section would do it. I see woocommerce has that ability - a simple "add new order" to the order manager area allows for manual back office order entry.
Thanks for your help.