[{id:"somePostId",comments:[{id:"commentId1",replies:[{id:"replyId1",likes:[{id:"likeId11"},{id:"likeId12"},]}]},{id:"commentId2",replies:[{id:"replyId2",likes:[{id:"likeId21"},{id:"likeId22"},]}]},{id:"commentId3",replies:[{id:"replyId3",likes:[{id:"likeId31"},{id:"likeId2"},]}]}]},{id:"someOtherPostId",comments:[{id:"commentId1",replies:[{id:"replyId1",likes:[{id:"likeId11"},{id:"likeId12"},]}]},{id:"commentId2",replies:[{id:"replyId2",likes:[{id:"likeId21"},{id:"likeId22"},]}]},{id:"commentId3",replies:[{id:"replyId3",likes:[{id:"likeId31"},{id:"likeId2"},]}]}]}]

db.collection.update({id:"somePostId"},{$push:{"comments.$[comments].replies.$[replies].likes":{id:"newlyInsertedLike"}}},{arrayFilters:[{"comments.id":"commentId2"},{"replies.id":"replyId2"}]})