Manager John McGlynn said of the signings: “Stephen joins the club after a very successful season winning the championship with Kilmarnock, playing in 40 games last season and playing a pivotal role in the Killie midfield.
"He brings huge experience to the club, as we all know he comes from a famous footballing family, and we believe that his winning mentality will be key to getting the best out of his teammates.
“He’s good on the ball, obviously at his age he has great knowledge of the game but speaking with him he still wants to learn and play with an ambitious club.”
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He added: “Gary is a striker who can also play behind a striker or coming in off a side. He’s gained a lot of experience mainly playing in the Championship, and we feel Gary will complement the way we want to play.
"He’s an intelligent attacking player who can link the play in and around the box, he knows the route to goal, he knows the runs to make, and he’s coachable and willing to learn.
“We signed Sean for Raith Rovers from Hibs in February and he just got better and better, he didn’t play much the season before due to injury but certainly showed how good he was both in defence and in attack.
“He’s very strong physically, got good pace, got energy and drive to get up and down the pitch, with a quality left foot, and at 23 years old we believe his best years are still ahead of him. We’re convinced he will be a great asset to the club.”
McGinn said: “I’m really excited to get going. The manager spoke to me while I was on holiday, and we got the deal done in a matter of hours.
"I was really attracted to the club and his particular management style. I can’t wait to get started at this football club.”
26-year-old striker Oliver added: “The goal for the season is to get promotion, and for me personally I want to play matches, score goals, and help the team to win games.”
While Sean said: ““I’m buzzing to get the deal done, I had some struggles with injuries in my time at Hibs, so I’m delighted to get here and start playing games. It’s great to link up with the manager again after spending last season with him, so I can’t wait to get started.”