Striker Parkin, on loan from Cardiff, missed out again at Huddersfield on Saturday with a hamstring strain, while Everton winger McAleny has been struggling with a knee problem.
"Jon tried to train on Thursday, but felt his hamstring, so there was no chance really," Knill told the club's official website.
"We're hoping he'll be fit for next week. It's the same with Conor. He's done work with Everton, but they've decided he's not ready yet, so they're keeping him until he's fit again.
"I'm hoping they're both back for the weekend because I want a competitive squad for the final two games, and I want to win those matches and finish the season well."