Duplication Backup Set to Tape duplicate all backup set

We need duplicate backup only last week backup set:

• First duplication      -  Alls backup set week 1
• Second duplication  -  Alls backup set week 2
• Third duplication      -  Alls backup set week 3
• Fourth duplication    -  Alls backup set week 4

My job is:

First Stage:

-          Full Backup SQL : 8:00 am. and 8:00 pm. (each 12 hours) , to disk , retention for 4 week

-          Backups SQL Logs: 12:00 am., 6:00 am., 12:00 pm., 6:00 pm.- (each 6 hours) , to disk, retention for 4 week

                  Segundo Stage:

-          Duplicate to Tape : Saturday 10:00 (each week) , source: all backup set

But this duplicate in tape:

• First duplication      -  Alls backup set week 1
• Second duplication  -  Alls backup set week 1 + Alls backup set week 2
• Third duplication      -  Alls backup set week 1 + Alls backup set week 2 + Alls backup set week 3
• Fourth duplication    -  Alls backup set week 1 + Alls backup set week 2+ Alls backup set week 3 + Alls backup set week 4

Any help about we need?