Okay, here's what you need (this is based on Victorian law):
The second brother is adopted and in the State of Victoria, and probably other States also, an adopted child has the same status as a biological child.
In inheriting the house from the parents they would probably be registered on Title as tenants in common. That is, owning half each, rather than joint tenants. Usually a married couple buys as joint tenants and when one dies, you don't look at their Will to see what happens to the house because the surviving partner is entitled to lodge a Survivorship Application at the Titles Office and the Title would be registered in the survivor’s name.
The brothers would wish to be registered on Title as tenants in common so they could leave their half interest in their Will to anyone, their own wife or children, or even, the other brother.
The brother who wishes to sell has a problem. Real estate can only be sold by having a written Contract signed by all owners and the purchaser or purchasers. The brother who wishes to sell would firstly look for a Power of Attorney where his brother has appointed someone to act on his behalf and approach him to arrange a sale. If that could not be done, he could then apply to VCAT (Victorian Civil and Administrative Tribunal) pursuant to its Act which is given jurisdiction in Part IV of the Property Law Act 1958 to make orders in regard to the sale of real estate between co-owners (whether tenants in common or joint tenants) and which can also authorise a Registrar of the Tribunal to sign documents on behalf of the absent brother.
If, on the other hand, the Title to the house had not been transferred by the Executors into the brothers' names, in that circumstance the brother could ask the Executors that the house be sold and the proceeds divided so that he receive one half of the proceeds and the other half be held by the Executors in trust for the absent brother until he can be located.
