Dynamic support for Nested Type data

I'm chasing a requirement where I may get new attributes from my source, which should be seamlessly indexed. Yes it is possible, but we also get nested types from source. By default, ES doesn't associate nested type. Dynamic templates also won't help me as the incoming data is not in our control and may contain a mix of nested and non-nested type. For this reason, we are thinking of other NoSQL solutions like Mongo where the trade-off is on search. But the need is search + filter + support for dynamic attributes.

Any help is appreciated.