How to manipulate the query plan so that I can have more control on memory grants?
I'm not sure I understand how a table is "too big" to update the statistics. When people start calling tables "too big" for anything, they usually start being candidates for table partitioning. In which case you can use incremental statistics to focus your stats updates on the active partitions (the optimizer won't use the per-partition stats independently, but it will still be beneficial for queries and reduces your maintenance because, presumably, not all of your partitions will have significant, or any, data fluctuations between every maintenance window).

Anyway, instead of trying to manipulate which operators are used in order to affect how much memory grant you have (which may make your performance or resource usage worse), why not use hints that control min/max grants directly? KB #3107401 talks about new query hints MIN_GRANT_PERCENT and MAX_GRANT_PERCENT that control the grant a query will get (the article says 2012 SP3, but these were also added in 2014 SP2). 

Tread lightly, though. My suspicion is you are trying to solve the wrong problem with the wrong solution. If the source of the problem is bad estimates, fix that problem.