differential and Incremental backups being accosiated with last full backup of servers

Hello,

I might not be a scholar when it comes to backup exec, but bear with me.

We currently have a backup exec 2010 server with 6 disksets, and we take a monthly full backup every month.
Is there any way to get around differential and Incremental backups being accosiated with last full backup on servers?

The goal is to be able to take a monthly full backup, then doing 2-3 incs or diff backups before changing to the next monthly disk (in other words, making the inc/diff accosiate with contents of the disk in question).

Any tips or ideas would be greatly appriciated.