I do think they are Brothers and Sister or maybe just friends, but to me this seems the most convincing.

I've actually always thought they were cousins... I have no idea why, but ever since I was a little kid I was convinced they were cousins to each other.

I always hoped Banzai and Shenzi were mates and Ed was a friend

I think Banzai and Ed are brothers but Shenzi is their friend this just always made more sense that is why I have to say other can't just pick one like that.

The mate thing with Shenzi and Banzai makes sense in fact I used to be convinced that they were Janja's parents

i always kind of thought that shenzi and Banzai were a couple and ed was either a friend or he and banzai were brothers