Wikipedia - Norwegian reserve football teams
Norwegian reserve football teams compete at all levels of league football within the Norwegian football league system apart from the top two divisions, Eliteserien and 1. divisjon. The highest league these teams can currently enter is the 2. divisjon, set at the third tier of the league system. The reserve teams are attached to their first teams with a "2" suffix and must play in a lower league than the first team. Furthermore, if a club's first team plays in the 1. divisjon, the reserves team cannot play in the 2. divisjon either.
If a reserve team ends up at a promotion spot when it is not allowed to be promoted, the promotion is awarded to best following team in the league standings which is allowed to be promoted. Also, a reserve team is forcefully relegated, regardless of the final league position, if it is no longer qualified for playing at that level - i.e. if the first team is relegated to a league level where the reserve team's level is no longer allowed. For example, if an Eliteserien team is relegated while its reserve team in 2. divisjon ends up at a secure place (or even a promotion spot), the reserve team is forcefully relegated to 3. divisjon. In such a situation, the best placed qualified team at a relegation position in the league that the reserve team is relegated from will keep its place. If there are no qualified teams at relegation positions (e.g. only reserve teams no longer qualified for the level), one extra team from the division below (the best placed qualified one) is promoted.