If you have three tables, you have at least two relationships as one relationship can only link two tables. Please list your tables and how each table directly links to any other table of the three. Also, please indicate if there are many matching records or just one for each side of a given relationship. (We call these one to many, many to one or many to many.)
It's likely that you have this relationship setup:
If you place fields from Table3 on your Table1 layout, the records present in Table2 will affect what records show from Table3 on your layout as the record in table1 must first match to one or more records in Table2 which in turn match to one or more recods in Table3
Without knowing more about your setup, there's not much more I can offer to help you out...