I'd say in this case you'd need to work with generalizations. (As a grid can have just one single entity) In other words, create a generalized entity which has the common attributes both entities share, and put the attributes they do not share on the specialized versions. If you then use the generalized object as grid object, the grid will show both entities, and you can show the common attributes.
So for example, I assume right now you got:
Now the solution would be:
For more information on inheritance and specialization, you could look here and here.