I had a similar experience. The parents sat at one table and the six kids were at another with my husband and me. I am a teacher so I know kids will be kids but they kept trying to touch the grill, were throwing paper at one another, etc. They really needed some adult supervision. Plus the youngest one (three-ish) cried the whole time because she wanted to sit with her mother.
Teppan Edo sits eight. I think it would be a little crowded with any more people.