Botany Bay Council has lodged an alternative plan for a council amalgamation in its area, which would create a 'port' council taking in Port Botany and the airport by taking parts of neighbouring councils, including Randwick, City of Sydney, Marrickville and Rockdale.

The proposal would take the the industrial areas south of Rainbow Street, Randwick, and McEvoy Road, Waterloo, to create what Botany mayor Ben Keneally says would be a more coherent way to manage transport and development around the two major gateways.

But the proposal threatens to push out the timetable for amalgamations. A public hearing on the proposal has been set down for May 27 and submissions can be made until June 12.

The proposal could have knock-on effects for other proposed mergers sanctioned by the Baird government, including the proposed merger between Waverley, Randwick and Woollahra, and possibly the merger between Marrickville, Ashfield and Leichhardt – though only a small sliver of Marrickville is involved in the rival Botany proposal.

The inquiries into these two mergers are completed, though the other factor in timing is the decision in a court challenge brought by Woollahra.

A spokesman for the minister said the Botany Bay Council proposal is now being examined by the delegate for the Boundaries Commission.

"No decisions have been made on any of the proposals, which are expected by mid-2016," he said.

Councillor Keneally said the new Botany proposal would bring transport and development between the two major logistics centres under one council.

"From a planning perspective this is more legitimate than the merger proposed by the state government between Rockdale and Botany," he said.

Meanwhile, more councils are heading to court to contest the process around proposed forced amalgamations.

Hunters Hill and Mosman have now commenced legal action and several smaller regional councils are also threatening to start cases. The strength of those will hinge on whether Woollahra council wins its case in the Land and Environment court, with a decision expected soon.

Mosman mayor Peter Abelson said the council had unanimously resolved to proceed with this action at its April 20 meeting.  "We have told the state government time and time again that council and the Mosman community want to stay independent," he said.  "Despite this the government has continued down a path that has been characterised by poor information, poor consultation and little to no regard for the wishes of our residents.

"We have not taken the decision to proceed with this action lightly, but we are fighting for our survival against a government that has overseen a deeply flawed process."