A new complaint against ex-DUP Minister Ian Paisley Jnr has been submitted to the Assembly's standards authority, the Belfast Telegraph has learned.
The move brings to five the number of Stormont and Westminster complaints against the MLA and his First Minister father - with all but one involving links to property developer Seymour Sweeney.
Mr Paisley Jnr is declining to comment publicly on the cases but is said to be privately confident that they will all be dismissed.
The latest complaint is understood to be based on Mr Sweeney's involvement last year with the Paisleys' constituency office premises in Ballymena.
It is believed to centre on whether his assistance should have been declared by Mr Paisley Jnr in the Assembly register of interests. The MLA is understood to be arguing that Mr Sweeney was involved as a DUP member for the benefit of the party as whole.
The new complaint has been made by a member of the public to the Assembly Standards and Privileges Committee and will be assessed by Interim Standards Commissioner Tom Frawley.
The Church Street office, which is owned by a company called Sarcon no 250, became the Paisleys' new Ballymena headquarters last summer.
Mr Sweeney was Sarcon no 250's sole director between May and October last year and secured a Bank of Ireland mortgage for the premises.
During this period, Mr Paisley Jnr spoke in the Assembly in support of Mr Sweeney's controversial visitor centre plan for the Giant's Causeway.
It has been stressed by the MLA that Mr Sweeney received no benefit from his involvement with Sarcon 250.
The firm was transferred in late October 2007 to Mr Paisley Jnr's father-in-law, who replaced Mr Sweeney as director.
The North Antrim MLA resigned as a Stormont minister earlier this year after months of controversy over his lobbying for Mr Sweeney. He continues to strongly deny any wrongdoing.
A separate long-standing Stormont standards investigation is, meanwhile, believed to be nearing completion.
Made by SDLP MLA John Dallat, it related to the fact that Mr Paisley Jnr's holiday home near Bushmills was registered for some three years in the name of Mr Sweeney's wife Carol.
Mr Paisley Jnr and Mr Sweeney have stressed that the politician bought the house at full market value and the delay in updating Land Registry paperwork was due to an "administrative hiccup".
Mr Paisley Jnr is understood to be expecting Mr Dallat's complaint to be rejected.
Mr Frawley will still have two further complaints against the former Minister to examine, including the recently submitted correspondence on the constituency office arrangements.
The new complaint has some similarities to an existing lengthy complaint made earlier this year by SDLP MLA Declan O'Loan, who also asked for a review of the £57,000 a year rental expenses claimed by the Paisleys for the Sarcon-owned constituency office.
The First Minister is meanwhile the subject of two complaints being examined by Mr Frawley's House of Commons counterpart, John Lyon.
The first was submitted last October by Mr Dallat, following a Belfast Telegraph report on a letter sent to the Heritage Lottery Fund in 2003. It protested at a grant refusal for Mr Sweeney's Causeway centre plans, and incorrectly claimed that the scheme had the approval of international heritage body Unesco.
A more recent complaint, from a member of the public, relates to Mr Paisley Jnr's £9,000-£11,000 a year job on his father's Westminster payroll. This Commons assistant post was on top of his posts as a Stormont Minister and MLA.
A preliminary inquiry on this case has been initiated by the Commons Standards Commissioner, who has to decide if a fuller examination is needed.