Cunningham Lindsey has agreed with Miller Fisher's receivers to act in a representative role for the group's loss adjusting work in progress.
The receivers have agreed to deliver all the outstanding files to the company's National Service Centre in Cardiff, for review and allocation to a dedicated management control unit.
A 24-hour helpline has also been installed to advise Miller Fisher policyholders.
Cunningham Lindsey says the move has been generally viewed as a positive one that will ensure any outstanding claims are resolved without further delay.
Cunningham Lindsey's chief executive Gerry Loughney commented: "Recent events in the insurance industry have generally put the reputation of the market at risk. We acted, with overwhelming market support, to assume a role that would put the needs of the policyholder first.
"Now we have secured the release of the files we have begun the process of working with our clients and Miller Fisher to finalise the arrangements."
Nick Dargan of Deloitte & Touche, Miller Fisher's receiver, added: "We are delighted to reach a successful conclusion which safeguards the interests of customers, and minimises disruption while maximising the potential for recoveries."
