If they return Chatfield to Utica or Domingue, they would have enough cap to activate Markstrom. They were at 154K after Boeser got activated, but to recall Chatfield had to put Markstrom on LTIR.
If Markstrom is ready to return - Domingue would likely be sent back down. Would free 1.075M in cap space - which is more than the cap needed to recall Chatfield.
If a team has no cap space and has less than 18 skaters + 2 goalies able to play, they can invoke roster emergency exception. They need to play 1 game short-handed then are allowed to recall a player who does not make more than 800K this season. That emergency recall wouldn't count against the cap but it's only valid as long as the team can't ice a complete lineup.