Reformers group operative Robert Assaf told the NSW Independent Commission Against Corruption he and another subject discussed potential vulnerabilities before the hearings began.
Mr Assaf also alleged former allies branded him a "rat" after he expressed a willingness to co-operate with an earlier parliamentary inquiry.
The commission is investigating alleged illegal political donations and branch-stacking spearheaded by the conservative Christian group.
Mr Assaf said he met with fellow Reformer and inquiry subject Jeremy Greenwood after receiving summons to the commission.
The pair met at a cafe in Belfield, southwest Sydney, and Mr Assaf accepted he left his summons open on a laptop knowing Mr Greenwood might look.
Counsel assisting Peggy Dwyer asked him if they had met to discuss the nature of evidence the pair would give at ICAC, which Mr Assaf also accepted.
"There was general discussion around (vulnerabilities) … and what other people might be thinking or saying," he said.
Mr Assaf agreed it seemed Mr Greenwood was trying to have him "align the messaging".
Disclosing a summons could constitute a criminal offence if it is found to have likely prejudiced the relevant investigation.
Mr Assaf said he was branded a "rat" for expressing willingness to appear before an preceding inquiry.
Earlier on Monday, Mr Assaf also detailed his apparent falling out with fellow Reformers co-founder Christian Ellis.
Mr Assaf said the state Liberals' right faction spread concerns, jokes and insinuations regarding Mr Ellis' connection to fugitive property developer Jean Nassif.
He also grew upset with Mr Ellis over finances relating to his work with Mr Ellis' consulting company Beckington.
By 2021, Mr Assaf was also concerned about Mr Ellis' dealings "raising funds for himself".
"He would use it under the guise of Reformers or using my name … I felt I had to make a concerted effort to really and intentionally split from him," he said.
Asked if he had concerns Mr Ellis might do something "at some point that was ICAC-worthy", Mr Assaf said it would not have surprised him if he thought that at the time.
The commission is investigating allegations Reformers solicited or accepted money from prohibited donors and sham contracts to assist their factional mission.
Businessman and party member Frits Mare is expected to appear on Tuesday followed by Damien Tudehope, a serving Liberal MP.