Mongoose - inserting a subdocument into another subdocument using push?

Question

Im new to javascript and mongoDB, and i've been trying to get my database to work for a few days and finally figured out how to do it using push yesterday, so i apologize in advance if there are ways to do this much more efficiently.

Anyway i have the following schema:

var baseLinesSchema = new Schema ({
    topName: { type: String, unique: true} ,
    baseLines: [{
        baseLineName: { type: String, unique: true},
        baseLineStart: String ,
        baseLineEnd: String,
        targets: [{
            target_Name: String,
            targetStartedAt: String,
            targetCurrentTime: String,
            targetEndedAt: String,
            targetStatus: Number
        }],
    }]
});

var allbaselines = mongoose.model('allbaselines', baseLinesSchema);

I can use baseLine.baseLines.push to insert a new baseline. What i want to do is insert a new target-subdocument into a specific baseLine (preferably using the baseline name) like

baseline.baseLines['baselineTwo'].push({targetName = "TargetOne"}, {targetStart = "2521212"});

What's the best way to do this?

Thanks!