Last season, Sisco, 21, slashed .317/.403/.430 in 116 combined games: 112 with Double-A Bowie and four with Triple-A Norfolk. He caught 24 percent of runners attempting to steal.
ESPN's Keith Law ranked Sisco 69th on his list of Top 100 prospects for 2017.
The Orioles signed Schafer to a minor league deal in December. The 30-year-old appeared in 26 games for the Minnesota Twins last season, slashing .238/.342 /.317 over 74 plate appearances.
Schafer was a third-round pick of the Milwaukee Brewers in 2008. He spent the first five years of his career in Milwaukee, appearing in a career-high 134 games in 2013.
Baltimore's remaining non-roster invitees include: