Declan Hainey's 15-month-old body was found in his home in Bruce Road, Paisley, in March 2010.
His mother Kimberley Hainey was sentenced to a minimum of 15 years in prison after being convicted of his murder in December 2011.
However, she was freed last year after being cleared on appeal.
She has been called to give evidence at the FAI, which is scheduled to begin on May 12 at Paisley Sheriff Court.
The inquiry will last nearly three weeks in a bid to establish the cause of Declan's death.