.
If you left them off the entry you will be disqualified.
If you lie about it they may well know about them from your background check and you will be regarded as having made a fraudulent immigration application - denial and possible ban from US.
If you lie about it and some how dont get caught, you can never bring them to come live with you, as they will check the records, find they existed before your entry, and strip you of your green card.
So if you left them off your entry, best not to waste your money on the medicals and interview, and try again next time.