The Seven-partner private client department of Edinburgh firm W&J Burness is to join Turcan Connell.
Five of the team are joining Edinburgh-based Turcan Connell as partners, while the other two will become consultants.
Turcan Connell will also acquire the Guernsey office of W&J Burness when the deal goes ahead in December when it will have 11 partners, three associates and 90 staff in all.
Turcan Connell is the demerged private client offshoot of Arthur Andersen-tied Dundas & Wilson.
W&J Burness chairman John Rafferty said his firm had opted to concentrate on commercial work because a mixed bag of commercial and private client work gave "a mixed message to the market". He said that the decision was made six months ago, although the demerger had been a private client group initiative.
Rafferty refused to comment on speculation that the demerger had been prompted by the fact his firm was in talks with an accountancy firm.
Turcan Connell partner Douglas Connell said his firm had started informal discussions with the group earlier this year following its own demerger.
He said it was significant that both the Dundas & Wilson and W&J Burness demergers had been initiated by the private client departments,
He claimed the merger would make Turcan Connell one of the leading charity and trusts practices in the UK.