Design/load Question

Hi. I am redesigning a database to be more normalized. There are 4 columns that appear in many of the tables that I plan to add to a new table. Here is what the database looks like now:table1 uniquecolumn1 uniquecolumn2 uniquecolumn3 samecolumn1 samecolumn2 samecolumn3 samecolumn4 uniquecolumn4 etc.table2 uniquecolumn1 uniquecolumn2 uniquecolumn3 samecolumn1 samecolumn2 samecolumn3 samecolumn4 uniquecolumn4 etc.table3 uniquecolumn1 uniquecolumn2 uniquecolumn3 samecolumn1 samecolumn2 samecolumn3 samecolumn4 uniquecolumn4 etc.If I add a 4th table with the columns that are the same in each of the tables, I'd have this:table1 uniquecolumn1 uniquecolumn2 uniquecolumn3 uniquecolumn4 etc.table2 uniquecolumn1 uniquecolumn2 uniquecolumn3 uniquecolumn4 etc.table3 uniquecolumn1 uniquecolumn2 uniquecolumn3 uniquecolumn4 etc.table4 samecolumn1 samecolumn2 samecolumn3 samecolumn4To link table4 to the other tables, I'd define foreign keys on table4 that reference the primary keys of tables 1-3. What I'd like to avoid is having a composite key on table4 made up of the primary keys of tables 1-3. That doesn't sound correct. How do I do this? Also when it comes time to load data, I know that I need to populate tables 1-3 first, but how do I then uniquely identify the rows in tables 1-3 that must go into table4? Thanks for the help!