Ok, I confirmed my answer.
Juveniles, including nonresident juveniles, do not have to have a LICENSE (except the Apprentice license if they don't meet the hunter ed req.) until age 13. So, your brothers will need no LICENSE.
If they are going to be hunting later in the season on the Special Season Antlerless hunts, they will need the Type 94 PERMIT.
To check a deer in, they will have to have their social security number. They WILL NOT be able to check it in online or by the phone App until they have a TWRA profile created for them. They will get that by going to a checking station for their initial check in, or by call the TWRA License Sales Div. ahead of time and creating the profile. AgaIn, it will require their SS#.