even in a large set up you still have a high risk that the dominant dragon will severely injure the smaller one.
With only a VERY FEW exceptions, males and females should NOT be housed together. The males will constantly try to breed and over stress the female. Beardies are NOT social dragons--they are solitary...Most breeders only put the male and female together for short periods--until the "deed" is done and then they seperate them.
Did you know that with just ONE breeding a female can produce multiple clutches of eggs--just a few weeks apart! Are you and your brother ready to invest HUNDREDS of dollars in incubators and housing for all of those babies. DO NOT think you will make money--you will be lucky if you break even and find homes for all of them...the market is saturated. Just one clutch of babies can eat 1000s of crickets in one week--and you will have them for at least 6 weeks...the babies will need to be housed in small groups to prevent tail nips...each set up will have to have its own lighting/heating...you will most likely STILL have young from the first clutch that you have yet to find homes for when the second clutch comes along.
Females should be full grown--at least 18 months is a common standard--BEFORE she is introduced to a male for breeding. They are capable of breeding much younger but at a serious risk to her health. Males can also have complications from early breeding.
PLEASE research this and get your parents approval BEFORE you do something stupid and end up yelling for help on the forums.
DM