The IFA Association's London and Southern region committees are seeking to stall IFA Portfolio's pseudo network Anglo Caledonian.
The regional committees say members have not been given sufficient information to make a proper judgement about the network's formation and want members to vote no at Portfolio's AGM on Friday.
The committees are also proposing two new directors for the Portfolio board in a bid to ensure their regions' views are represented.
In letters to London region's 300 and South-east region's 320 members, the two committees say: "Potentially, there are severe financial implications for the IFA Association and its members."
Both committees will vote against the changes and are calling on members to attend the AGM or send proxy votes.
The two IFAs proposed for the Portfolio board are Boyd & Associates principal Ken Boyd and Rolton Associates director Clinton Askew.
The committees are particularly concerned about the £5,000 payment each director of Portfolio can make to receive 5,000 shares in the new network. Anglo Caledonian member firms can also get share options worth £5,000.
The committees say: "It would appear that the Portfolio directors and their nominees could benefit financially from these proposals whilst current Association/Portfolio members would be excluded."
The committees are also concerned at proposed changes to Portfolio's corporate constitution which, if passed on Friday, will see the creation of a separate membership structure from the IFA Association and changes to the rules in the event of a wind-up.
Portfolio managaing director Mike Owen has faxed a three-page response to all South-east region members to "put the record straight". He says: "There has been a campaign of black propaganda for many weeks now which has been both personal and vicious, directed at the board of IFA Portfolio."