Late last week, Sophie Monk addressed Grant's 'secret girlfriend' rumours, claiming she didn't believe them.
Speaking to Kyle and Jackie O, an anonymous caller interrupted Sophie's interview alleging that his sister is friends with Grant's 'secret lover'.
After the 'source' claimed that Grant's appearance on Love Island was just a 'publicity stunt' to make him famous, Sophie shot down the rumours.
'There's no way! Nah, I don't reckon...I've seen [Grant with Taylor],' she said.
When asked by Sophie how close he is to the alleged girlfriend, Kyle and Jackie O's 'source' said he had called his mother and sister to confirm the rumour.
However, he refused to reveal the name of Grant's 'girlfriend'.
The winners of Love Island Australia will be announced on Thursday night's episode. The couple who win will receive $50,000.
