Can I stop my kids seeing the ex’s new partner?

I’m often asked if there is a way for a parent to stop their child spending time with the other parent’s new partner. The short answer is no. Both parents have parental responsibility and they are able to exercise that responsibility in whatever way they see fit. The only exception to this would be in situations where a child was spending time with the new partner and the Court considered it unsafe for that child to be with that person, this is very rare.