I am submitting my paper to a journal, but a very small part of the work was previously presented in a quite prestigious international conference (although not the top). The journal policy allows for this, given the revised journal version has at least 30% novelty as a thumb rule. It even allows some copied texts and figures, which I do not have.
So from what I see, it is not absolutely necessary for me to mention the conference edition as part of this work although I am citing it as relevant, along with other references. But researchers will understand that it is not black and white, but gray. The previous research will always somewhat influence the future research.
If I do mention the conference presentation as part of the submitted work, will it make the work more authentic to the reviewers? Will they somehow take it more seriously, so to say? I am interested in the opinions of experienced reviewers and editors.
Just to make it clear, in my field, journals are considered more prestigious and they publish the more refined, expanded versions.
Also, this journal has an anonymous review process, but not double-blind.