We call this Cross Selling. Which is where this post
http://forum2.sambapos.org/index.php/topic,192.0.html ended up.
On the Restaurant terminal, select the Take Away menu, select the items and close the ticket.
Switch back to the Restaurant menu, open the ticket and settle.
This means you can use the Restaurant cash and the Work Period Report will show the Cross Sales between departments, and who owes what to who.
The only thing, is the receipt will be from the Restaurant (Restaurant name, not Take Away name), unless you use Product Categories in your Print Jobs and allow both departments (and terminals) to print to both receipts. If both departments trade with the same name, then no issue with printing - leave as is.
We use this between Bars & Restaurants, as the Restaurant does not sell alcohol, but customers want to put Bar items on their Restaurant ticket, and pay for the lot at the end of their meal. It means that they can pay at either department and you know that all items have been paid for.