A Ponzi-scheming attorney snookered his in-laws out of more than $4.6 million in a real-estate scam, Manhattan prosecutors charged yesterday.

Robert Cassandro, 47, of Woodbury, LI, pleaded not guilty to grand-larceny charges carrying anywhere from two to 25 years in prison.

Prosecutors agreed to a promptly posted bail of $50,000 — surprisingly low, given the dollar amount involved in the Manhattan-based alleged swindles.

Cassandro tapped multiple people to invest in the same homes, and essentially pocketed most of the money, save for some token payments to some victims to keep up the charade, prosecutors said.