Rhino elephant carriages

I just tried putting carriages onto a black and greater rhino but it turned them into standard rhinos is this right as the crafting menu has different options for the rhino.

I was expecting a greater rhino and a black rhino with carriages on them.

Thanks

You cant have a greater caravan rhino/elephant. It is either great (stat-wise) or caravan (more slots).

What is the need to have all the different crafting options then?

so that you can make a caravan dlc pet from any existing version of the rhino/elephant