Updated August 14
Nationalist MP Hermann Schiavone, one of Adrian Delia's closest associates, will rejoin the party's parliamentary group on Tuesday after the party's Ethics Board decided that he had broken no rules when he met 17 Black owner Yorgen Fenech.
The meeting, the board concluded, was "an error of judgement".
Dr Schiavone had suspended himself from the group after the April meeting which he attended with PN council president Kristy Debono was revealed by The Sunday Times of Malta, raising a storm of protest.
Dr Schiavone and Ms Debono met Mr Fenech to discuss a potential sponsorship opportunity for a conference they were organising.
Mr Fenech, who serves as a director of the Tumas Group as well as of the Electrogas power station consortium, had been revealed to be the owner of 17 Black, a secret company which leaked emails suggested, was created to funnel money to companies owned by minister Konrad Mizzi and OPM chief of staff Keith Schembri.
Ms Debono subsequently admitted an error of judgement.
Dr Schiavone, in suspending himself from the parliamentary group had told Dr Delia in a letter that: "Despite knowing I did nothing wrong, I still feel I need to carry responsibility for my lack of attention." He apologised for his action and had invited the party to investigate the case.
In a statement on Tuesday, the PN said that after Dr Schiavone suspended himself, his case had been referred to the party's Ethics Board.
The board found that Mr Schiavone had not breached any party rule or instruction, nor had he broken the law, but this was an error of judgement. It therefore recommended that there should be no further action.
The board's decision was confirmed by the party's administrative council.
Since suspending himself, Dr Schiavone had kept a low profile at party events and on Facebook. He nevertheless took part in a confidence vote concerning party leader Adrian Delia.
But in a Facebook post late on Tuesday Dr Schiavone said he was returning to the party "with greater energy".
Norman Vella quits party
The party decision to reintegrate Dr Schiavone was met with dismay by former electoral candidate Norman Vella, who said on Facebook that he would be quitting the party.
"I would be failing myself and those who showed confidence in me if I did not express my anger following the decision," he wrote.
"I have decided to take the gentlemanly way forward and resign as [party] candidate, councillor and member".