A legal chain of custody requires the samples to be collected in the presence of a third neutral party at a lab or hospital facility where all parties are photographed to verify their identity. Test results are mailed to adults listed on the authorization form which is supplied with the kit. No other party will be able to request results without a written consent form from the purchaser. There are no age requirements. No permission is required from Spouse, Doctor, or Attorney, to obtain your alleged children samples.
Special samples can be used with the home DNA test kit, however, additional charges apply.
See this link for special sample pricing. The additional cost is not refunded if no DNA is present on the special sample. If the alleged fathers are brothers or father and son then they should each be tested at the same time. Related individuals share more of their genetic code than unrelated individuals. When there are related possible fathers, not testing all parties could result in falsely implicating the alleged father.