Have entity join a player's team, regardless of their team

Is it possible to store the info of a player's team and pass it as an argument for a /team join command? For example, a player is a member of the team "knights". They trigger a command that causes a nearby skeleton to join their team. Another player is a member of the team "bandits" and does the same thing on a different skeleton. They both trigger the same command that automatically fills in whatever team they are a part of. Is this possible at all, or do I have to hardcode the team name for each case?