The Sussex and Brighton Strategic Authority will meet for the first time on Wednesday.
The commissioner will report to both the Health Secretary and Greater Manchester Mayor Andy Burnham.
Ministers are considering a proposal to expand Brighton into East Sussex and to split West Sussex.
Attempts to change the government's devolution legislation to get a deal for Cornwall have failed.
The network of 15 councils in Essex will be abolished and replaced.
The current ones will all be scrapped and replaced by new authorities.
Four new local authorities are heading Hampshire's way, with the Isle of Wight staying as it is.
Supporters of more Cornish devolution have repeatedly fought against any forced links with Devon.
Leigh Ingham says a new Stafford town council will add an unnecessary layer of local government.
