McMillan, 26, has split the 2014-15 season between the Marlies and Orlando of the ECHL. In 22 games with Orlando, he has 14 points (five goals, nine assists). The Brandon, Man., native has appeared in 13 games for the Marlies this season, registering one assist.
The 6-foot-1, 200-pound forward was selected by the Minnesota Wild in the seventh round (200th overall) of the 2007 National Hockey League Draft. McMillan has played in 16 career NHL games, scoring two goals and three assists (five points), all with the Wild.
McMillan has played in a total of 330 career American Hockey League games, tallying 41 goals and 38 assists for 79 points. He was a member of the Western Conference champion Houston Aeros in 2011, scoring five points (three goals and two assists) in 21 Calder Cup Playoff games.
Sivak, 32, has 10 goals and 16 assists for 26 points in 29 ECHL games with Stockton this season, adding one goal in six AHL games with Bridgeport.
Sivak is in his third North American season after playing 12 professional campaigns in Slovakia and his native Czech Republic. He has appeared in 18 career AHL games with Bridgeport, Abbotsford and Worcester, totaling five goals and one assist.