You can't link layouts, you link table occurrences--these are the boxes connected by lines you see in Manage | Database | Relationships.
When you create a new layout, you also specify from which table occurrence you will access/display records. This is what you select in the "Show records from" box in Layout Setup...
If both layouts refer to the same table occurrence in layout setup... then you are working with exactly the same set of records in the same underlying data - source table. This may or may not be what you need here.
Many folks find the terms Table and Table Occurrence confusing. To learn more, click the following link:
Table vs. Table Occurrence (Tutorial)