Defender Younger and midfielder Clayton both signed 18-month deals on arriving at the club in the last week.
And McSheffrey has confirmed their stays could be extended by a further 12 months if they make a specific number of appearances for Rovers during the initial terms of their deals.
Speaking about Clayton’s arrival, he said: “If he hits targets in terms of games then his contract rolls on for an extra year, and that is the same as Ollie Younger.
“We’re planning for the longer term and giving players incentives to earn a longer deal with the club.
“We’re seeing the bigger picture and we’ve been shrewd with who we’ve brought into the group.”