I am currently a PhD student and have been advising an undergraduate student on their thesis, which will eventually contribute to part of my own work. Their committee currently consists of my faculty advisor and another faculty member at my university. The problem I see is that neither my advisor nor the other faculty member have substantial research/experience in the area of the thesis since I am exploring an intersection of 2 fields and the university does not have any faculty in this specific area.
I feel that the current committee is well suited for evaluating the quality of the research methods but not the novelty or accuracy of the work done. This student has put in a lot of effort and I want them to receive feedback and critical analysis on their work. I can easily provide this feedback in our regular interactions, but I don't want other universities' admissions departments to disregard the work due to the committee selection.
My own work in the field is not well known or well cited so my name doesn't bring any value to the list of names on the thesis committee, but as we don't have other faculty in the area, I am not sure what else to offer.
Is it reasonable for me to suggest being added to the committee? Is it common/acceptable practice for a PhD student to be on an undergraduate thesis committee?