Before =

namespace X.Y.Z
{
class Foo {}
}

namespace X.K.A
{
class Bar
{
void Method(Y.Z.Foo foo) {}
}
}

Rename namespace X.K.A to X.K.Y

Result, Y.Z - highlighted

namespace X.Y.Z
{
class Foo {}
}

namespace X.K.A
{
class Bar
{
void Method(Y.Z.Foo foo) {}
}
}