Parkin has undergone knee surgery and has gone back to parent club Cardiff, but Knill is hoping the 30-year-old has not played his last game for the Iron.
"I think we would all like Jon Parkin, but he's not our player," Knill told the club's official website.
"At the moment we have no idea what Cardiff want to do and probably won't know until they know what division they're going to be in.
"They have a great chance of going into the Premier League and at the moment that is their focus, so all we can do is wait and see and monitor the situation."
Parkin scored six goals in 14 appearances for Scunthorpe after arriving in early February.