The spokesperson said HNZ had yet to discuss the purchase with HDC.
The $5.2 million suspensory loan is interest free and expires in 2029 at which point no payments are required if the housing has been kept as social housing.
However, even once the properties are sold and the loan transferred to the purchaser, HDC - under the terms of the loan - has to guarantee the loan until it expires, and HNZ can call on HDC for repayment if there is a "serious breach" by the purchaser.
Earlier this year, Horowhenua GreyPower's Lew Rohloff described the loan guarantee as "exposing the serious risk of HDC's liability to Housing New Zealand" while HDC chief executive David Clapperton said the prospect of default was unlikely.
Sisters of Compassion also owns 93 Upper Hutt social housing units, which it purchased from Upper Hutt City Council 17 years ago.
The Upper Hutt units are managed by Compassion Housing, a registered community housing provider owned by Sisters of Compassion that HDC has said will also manage the Horowhenua units once sold.