Wesley Robinson, 21, and Kevin Millard, 19, both from Hertford, will appear before magistrates on Monday.
The officer's son - along with two other people - has already been charged with blackmailing his 70-year-old grandmother.
Mark Bayliss, 20, of Cheshunt, Hertforshire, appeared with Russell Robinson, 18, and Laura Mason, 22, both from Bengeo, near Hertford, at Stevenage Magistrates Court.
They are jointly charged with blackmailing June Baker of Much Hadham, Hertfordshire.
Mr Bayliss, the son of an east London sergeant, was arrested last week in connection with the alleged blackmail.
They were remanded in custody until Tuesday.
The men are charged with "being concerned with others in blackmailing Mrs June Baker".
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