Relation ship build query

I have 2 tables
one is Fact Table and Customer
Fact Table fields are



Originator nvarchar(60),
[Customer Number] nvarchar(7) ,
Cust_Seq int FOREIGN KEY REFERENCES Customers(cust_num),

[Item code] nvarchar(10) FOREIGN KEY REFERENCES Item([Item code]),
[DateKey] INT FOREIGN KEY REFERENCES DimDate(DateKey)

and
Customer Table
cust_num nvarchar(7),
cust_seq INT PRIMARY KEY,
Company_name  nvarchar(60),
Address1  nvarchar(60),
Address2  nvarchar(60),
Address3  nvarchar(60),
Address4  nvarchar(60),
City  nvarchar(60),
Zip_Code  nvarchar(60),
County_State  nvarchar(60),
Country  nvarchar(60),
Telephone  nvarchar(60),
Email  nvarchar(60)


My question is

Customer Number is can't take unique,but custpmer sequence number can take unique.
becuase one customer has many orders and but customer sequence number will generate unique number according to orders(0,1,2,3...etc)

if i comapre with Fact table cust_seq field and customer table cust_seq is can't equal,becuase i will get wrong results
for example customer1 and customer 2 has same sequence number.

So can some one show me how to combine Customer table and Fact Table using which Fields(This for Dataware House).
and i need custo_seq becuase some time some time same customer address is different according cust_seq number.