asp.net - Creating list of users when developing an organisational hierarchy in C# -

so have build hierarchy whereby admin can create teams , sub-teams. there can infinite sub-teams , each team has have manager member of it's parent team (but not manager of it's parent team).

my issue this: how create list of users admin choose (when creating sub-team) whereby user neither manager nor member of of sub-teams parent teams?

i using linq sql in asp.net, , database schema contains follows: team - teamuser - user

team contains fields such teamid, teamname, parentteamid , managerid. teamuser made of teamid , userid , user made of userid , name , contact info etc.

at moment code looks list selectlist

viewbag.userid = new selectlist(db.users.where(u => db.teamusers.where(t => t.teamid == id && t.userid == u.userid).count() == 0), "userid", "firstname"); 

the following method receives subteam and:

1. marks manager ineligible,
2. traverses parents of subteam, marking users in parent teams ineligible
3. then returns list of ids of users have not been marked ineligible.

here's code:

public static list<int> geteligibleusersforteam(team subteam) {     list<int> ineligibleusers = new list<int>();     ineligibleusers.add(subteam.managerid);     team parent = db.teams.find(subteam.parentteamid);     while (parent != null) {         ineligibleusers.addrange(parent.users.select(x = x.id).tolist());         team parent = db.teams.find(parent.parentteamid);     }     return db.users.asenumerable().where(x => ineligibleusers.contains(x.id) == false).tolist(); }