boys

My first and earnest advice is to you to get checked your hubby's chromosome first. If the chromosome responsible for boy child is absent in your hubby then need not to look for third child. Third one will also be a girl. There are other methods also available with doctors which can be applied for. Better you consult renowned doctors in this field which will be more helpful. Though there is no lack of advisers in mylot community too. You will receive hundreds of advices here within few days. Such person will also make comment who is completely not aware of this fact. For boy child, try to improve the percentage of responsible chromosome first. ( I think it is X Chromosome)

hello and welcome to mylot

You can't guarantee that. It's whichever sperm gets to the egg first.