Temporary List In Gridview

Hello, i have a class Client that have many Printers, in the moment that i create the client, i have to add the printer list ( printers are showed in a combo and have a button Add), and at the end, include the client with the list of printers.

How can i make a temporary list to save the printer list and show in a gridview? I can’t save the relation until client is created.

Thanks in advance.