Ime none of my dats have ever bothered any other tank mate other than dats. That being said, when provoked, they will attack. As long as the Sevs aren't nippy you should be fine.
I wish they got nippy with him, but they never got the chance. Threw them all in and he went crazy..chasing them back n forth till i rescued them with the net. He's just much bigger then them and prob would of done some serious damage if i kept them in. Thinking about grabbing a few of the overpopulated sunfish from a local pond and testing them out for as long as it lasts. Maybe he'll get sick of chasing them and the sevs can be reintroduced.lol