The legal base for native titles claims in the ACT is very doubtful.
There may be good moral arguments for giving control over land in the ACT to Aborigines, such as joint management of Namadgi National Park, but the legal necessity is doubtful.
Native title, as explained in the Mabo case, exists at common law unless it has been extinguished by some inconsistent act by the executive or legislature that goes beyond the mere assertion of sovereignty by the Crown. The High Court says, for example, that freehold is inconsistent with native title. Residential leases, roads and public works are almost certainly inconsistent. Some pastoral leases are not, according to the Wik decision.
The question in the ACT is whether the surrender early this century by the Crown of NSW of all of the territory to the Commonwealth for the purposes of a seat of government is inconsistent with native title.
There are several arguments to say native title was extinguished by the transfer. The several Seat of Government Acts make it clear the transfer of the land was complete so that the Commonwealth could do what it liked with the land, making it clear it was more than a transfer of mere sovereignty. The Constitution says (though it is ambiguous) that the land shall be vested in and belong to the Commonwealth, which is inconsistent with native title.
Several Commonwealth statutes say that the maximum estate to be granted in the ACT is a 99-year lease, though native title is not a grant but something that came into existence eons ago.
But the whole legislative and constitutional scheme of setting up the ACT was one to provide a national capital with a hinterland to provide water and other needs of the capital, and that is inconsistent with native title as laid down by the Mabo case.
Further, the Federal Government and Parliament might want to have a say before the ACT Government acts. Perhaps a good first step would be to find out the legal position. In the long run it might be more satisfactory to hand over land and share management of national parks out of moral, rather than legal, obligation.