To help you, we need to know what fields you are using to link the two tables. Also, does your contacts table have a more than one "Name "Field? IE First_Name, Middle_Name, Last_Name.
field in both tables that identifies the person with a unique id. (Contact_id)
Are you using a field in both tables that identifies the person with a unique id. (Contact_id) ?
You have an easy to solve problem once you explain the desired result.
You also mentioned you are using a look up. Can you clarify what you actually what the end result to be.
First I am using the surname field to link the two table.
Yes I have a First_Name, Badge_id, email, and I do have a Contact_id.
I need to look/search the surname e fill the First_Name, email and so on ... fields.
If you were performing a find by surname you would find all records with that surname in your found set.
If you used a relationship to set up a portal, you would see all related records with that surname in your portal.
But if you set up a calculation that refers to the records in the related table, with most expressions that might reference fields in the related table, the expression just references data in the first related record. Certain aggregate functions such as List could, on the other hand, return data based on all the related records.
A value list based on Surname in many cases would also show just one instance of any one surname value.
From what you describe, it sounds like you might set up a portal listing all records with a surname entered by the users with buttons in the portal row (or the fields of the portal row set up as a button), that then enables the user to enter data from the portal row that they choose to click.
To link the two tables you need a unique ID. Go back and create the field Customer_Id, or whatever else you want to use. Create the field in both tables. In the contacts table, be sure to set the validation to require a unique value. In the contacts table, Auto enter a serial number in the Customer_id field.
The trick will be to replace the ids in the 2nd table
Actually, linking by surname can be useful, but only as a way to get a list from which to select a record and get it's primary key copied over to a foreign key. In other words, a special use relationship used during data entry to set up a proper primary key to foreign key relationship.