Assembly questions have been tabled asking if First Minister Peter Robinson ever lobbied for the two developers who stumped up £50,000 at the request of his wife.
The money was paid in the summer of 2008 by Ken Campbell and Fred Fraser to support a cafe venture by Iris Robinson's then 19-year-old lover Kirk McCambley.
Mr Robinson learned of the payments several months later, and discovered in March last year that Mr McCambley had been involved in a sexual relationship with his wife.
Mrs Robinson did not declare her involvement with the developers' £50,000 in the registers of interests at the Assembly and Westminster.
Mr Robinson has been criticised for not reporting these non-declarations to the authorities, and for not persuading his wife to make belated register entries.
He has rejected the criticism and maintained he acted properly at all times.
It was revealed last month that Mrs Robinson lobbied in support of a proposed housing development by Mr Campbell in the summer of 2008. She had also made representations on two previous planning applications involving Mr Campbell and Mr Fraser.
The details were provided to the Assembly by DUP Environment Minister Edwin Poots. He said a “definitive” list of all such lobbying by Mrs Robinson could not be provided, as a manual trawl of records would involve “disproportionate” costs.
The questions on the First Minister were tabled by Green Party MLA Brian Wilson. He asked Mr Poots to “detail any representations” made by Mr Robinson since 2000 in relation to planning applications by Mr Campbell, Mr Fraser or “associated companies”.
In a question to Mr Robinson's own department, Mr Wilson asked if “any declarations of interest were made by the First Minister in relation to departmental or Executive discussions” on the future of Belfast's Titanic Quarter.
Mr Campbell is a member of the Titanic Quarter advisory board.
The Green Party MLA also requested details of “any planning enforcement actions initiated on developments owned by Fred Fraser or associated companies”.
The DUP has stonewalled questions on whether Mr Fraser financially supported the party.