i have got 3 tbl Customers, Orders, and Selling Channels.
i want to create a look up in the orders tbl for the customers last name, but it must me for customers with identical Selling Channel.
in every customer row there is selling channel field and in every order there is a Selling Channel field, the customers that will appear in the order must be only from the same selling channel of the order.

Thanks

do not create lookups at table level. instead, create a form for data entry, and manipulate your lookups (as comboboxes) there. once you've a form setup, it is easy to filter for customers with particular values in certain fields.

remember:
tables are for data storage only
queries are for data manipulation (such as calculations)
forms are for data display/entry/editing
reports are for pretty data display and other functions