Customer can have multiple orders and multiple address
I don't think your existing relationships will support multiple addresses for the same customer. A relationship that links by an address ID might be a better option for you.
But that's a different issue. To address the specific problem...
Orders::F_Customer_ID can be formatted with a value list where the list has Customer::P_Customer_ID as field 1 and a Customer name field from this same table as field 2. (You may need to add a calculation field that combines first and last names to use for this second field.) The user can then select a name from the value list, but it actually enters the ID number to link the order record to the customer's record in the customer table.
If you pull down the list and can't find the customer, a "new customer button" can be included that creates a new record in the customer table. If all the needed fields are also present on your Order layout, you can then just fill in the information directly on the order layout. If not, your script would need to use a different layout for new customers. This can be just a layout change or you can get fancy and use new window to open a window to the new customer layout so you can enter the data for the new customer and then close the window to return to the order layout.
This is the simplest approach, but not necessarily the best. It can make searching for a customer very tedious due to having to scroll through a very long list of customers and handling cases where two customers have the same name can be a problem. (Sorting your value list by customer name in this value list will drop out any customers with duplicate names.)
There are several scripted approaches that use either an auto complete drop down list based on the customer's name or a filtered "search portal" to do a name based search to find an existing customer. Each of these approaches use a script to handle duplicate customer names and also to enter the selected customer's ID number.
Here's a demo file that illustrates several such approaches: http://www.4shared.com/file/plr_jbkk/EnhancedValueSelection.html
If you see a technique you like but can't figure out how it works, let me know in a follow up question and I'll help you understand it.
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Hello Phil , Thanks for the help. it worked.