In fall of 2006 I acquired a 12 yr old slider living with a 5 yr old stinkpot. The stinkpot would run and hide whenever the slider started moving around. After 6 months the slider starting nipping at the stinkpot, so I seperated them. The little stinkpot is SO much happier now, coming out to bask, wandering around the bottom for food, etc. So I would plan on eventually splitting them up, because the size difference would be too stressful.