Acronis will do what you want. It will even give you a better way to do what you want.

For example, you take a full backup once, then set it up to do an incremental backup, and keep a maximum of 3 incremental backups. It will consolidate the old incremental backups into the full backup automatically. Even though the incremental backups are stored in separate files, Acronis organizes and displays them as a single backup. When you open the backup, you pick the date you want at the top level.

Or you can set it up your way also, and cap the number of full backups that it keeps.

There's pros and cons to both methods.

You can do a full restore from any of the backup types that Acronis supports.

-David