If you have made your package(s) in the campaign but afterwards there are newly made Design items which also need to be in the package(s) then there is a possibility for it.

Go to the Packages tab and then click on the Refresh button.

Now you get the massage:
​Are you sure you want to update all the campaign packages? Only new publication items will be added to the campaign package. Existing package items will not be affected.

Then click on 'Update' to confirm.

Now the package is updated with the new added Design items of the publication.