Combine two OR-queries with AND in Mongoose

I want to combine two OR-queries with AND in Monoose, like in this SQL statement:

SELECT * FROM ... WHERE (a = 1 OR b = 1) AND (c=1 OR d=1)

I tried this in a NodeJS module which only gets the model object from the main application:

/********** Main application ***********/
var query = MyModel.find({});
myModule1.addCondition(query);
myModule2.addCondition(query);
query.exec(...)

/************ myModule1 ***************/
exports.addCondition = function(query) {
  query.or({a: 1}, {b: 1});
}

/************ myModule2 ***************/
exports.addCondition = function(query) {
  query.or({c: 1}, {d: 1});
}

But this doesn't work, all OR-conditions will get joined together like in this SQL statement:

SELECT * FROM ... WHERE a = 1 OR b = 1 OR c=1 OR d=1

How can I combine the two conditions of myModule1 and myModule2 with AND in Mongoose?