Absolutely! In fact, this is a key factor for success. Once the taglines start rolling in, let the creatives know what you think about their tagline suggestions. You can score and give individual feedback. You can also update your brief if you want to address all participants in your project. They are happy to make changes and iterate on their suggestions.
When you score each name suggestion (1 to 5 stars), your score and comments are private. Only you and the individual creative will see the star rating and comments on their tagline. Updates to your brief are public for all participants in the project.