Can a grand daughter and grand son of two different sisters get a married?

So, they would be cousins? It depends on where in the world this is. Some places will allow it, while others won't.

I think that is far enough out that it should be OK in most places.

Grand son of a sister would be a second cousin and is allowed to marry.

Roheet Jaiswal,

From your Hindu, I presume, name, it seems you are from India, at least an Indian, by inheritance. About marriage, b/w whom you ask, it is allowed LEGALLY, but not so SOCIALLY in most of the families or social groups. But, for muslims and fro certain ARORA families, it is okay. So, if you asking from legal point of view, no need to worry, but if it is otherwise, just look at the social norms of your family and society. Some people have misgivings about bio-consequences, and for that - do not worry - biologically, in terms of the child/baby born, no problem!

Good luck, if you are one of the duo!