Benjamin Field, 28, explained the "100 clients" file was not just a list of future targets but of people who could help him.
Field is on trial alongside Martyn Smith, 32, accused of murdering author and former teacher Peter Farquhar, 69, and conspiring to murder retired headmistress Ann Moore-Martin, 83.
The English literature graduate admits deceiving Mr Farquhar and Miss Moore-Martin into believing he was in a relationship with them both.
Field also admits "gaslighting" the pair, who were neighbours in the village of Maids Moreton, Buckinghamshire, in order to benefit financially from their wills.
Mr Farquhar died in October 2015, while Miss Moore-Martin passed away in May 2017.
Giving evidence for a seventh day at Oxford Crown Court, Field took the jury through his "100 clients" list.
He named his own parents, Ian and Beverley, paternal grandparents and two co-accused, Smith and younger brother Tom Field, 24.
Field also named a former long-term girlfriend, members of her family, ex-partners, one-night stands, and other friends and acquaintances, such as a recently widowed woman who owned her own home.
"People who maybe useful to me, either as targets of fraud or in other ways," Field said.
He explained that his brother Tom's inclusion on the list was as a "prop" for his fraud of Miss Moore-Martin.
"He was used and manipulated by me," Field said.
The court heard that 101-year-old widow Liz Zettl, who Field and Smith are accused of committing will fraud against, was also on the list.
But Field insisted she was not a "target" and was only named because she was Smith's landlady.
"She was a useful person for keeping Martyn Smith in Buckingham and within my sphere of influence," he said.
Other people named were linked to Stowe Church, where Mr Farquhar had worshipped, and who Field believed might be able to "support my studies of theology".
"I thought they might be financially supportive of my phoney career in the ministry," he said.
Asked to explain the list, Field said: "I suppose I was setting out to make a very broad type of list and the title amused me.
"Some of them are targets. I didn't see them all as targets. It is a title I have given to a very broad list. It just amused me at the time."
Field told the jury that co-accused Smith, who he became friends with while studying at the University of Buckingham, had been "manipulated and deceived" by him.
"I was keeping secrets from him and lying to him and getting him to do errands for me," Field said.
Field has admitted defrauding Miss Moore-Martin of £4,000 to buy a car and £27,000 to buy a dialysis machine by claiming his brother, Tom, was seriously ill.
Field and Smith, a magician, deny charges of murder, conspiracy to murder and possession of an article for the use in fraud.
Field, of Wellingborough Road, Olney, Buckinghamshire, also denies an alternative charge of attempted murder. But he has admitted four charges of fraud and two of burglary.
In addition, Smith, of Penhalvean, Redruth, Cornwall, denies two charges of fraud and one of burglary.
Tom Field, also of Wellingborough Road, Olney, Buckinghamshire, denies a single charge of fraud.
The trial was adjourned until Thursday.
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