New posts in Caerphilly UA, a merger of Islwyn BC in Gwent and Rhymney Valley DC in Mid Glamorgan, will be restricted to a pool of employees allocated to Caerphilly from the two districts and the two counties.
Employees in Gwent and Mid Glamorgan CCs are allocated to the new authorities according to their own preference, which they have already indicated. Staffing structures will be produced in a fortnight.
The restrictions mean that staff who have indicated their preference before knowing how many posts are available in the new authorities will not be able to compete for jobs outside their chosen council.
Unison branch secretary for Mid Glamorgan Pam Baldwin said the county had resisted the arrangement because it had not wanted 'to lock people into one authority'.
She said staff might have to be released to apply for less sought-after jobs in Caerphilly UA and Merthyr Tydfil UA.
Gwent CC personnel director Alan Tait defended the restrictions. 'We don't want a free for all from both counties, which would be complicated to administer,' he said.
Welsh Staff Commission advice is that all new posts should be advertised and, by implication, open to county-wide competition. Alternative local agreements should have its approval, it says.
'To date no unitary authority has approached us formally with details for proposed local arrangements,' said commission secretary Marie Knox.
Mr Tait believed the counties had commission approval for the local agreement.
In Mid Glamorgan 160 people over 50 are taking early retirement.
The county wants Cardiff UA to take on some of its Cardiff- based staff. Mid Glamorgan CC personnel director Geoff Dorracott said negotiations are at an early stage: 'We are trying to open up a dialogue.'
Mid Glamorgan has set up an exchange bureau where staff who are not happy with their transfer arrangements can swap posts. There have been queries from 40 employees out of 2,000 about appealing against their transfers.
Staffing arrangements at Aberconwy and Colwyn UA have not yet been agreed. West Glamorgan CC will follow Staff Commission advice and advertise new posts to all county staff. Dyfed CC and South Glamorgan also plan to advertise county-wide.