public static class MyExtensions
{
    // Write custom extension methods here. They will be available to all queries.

    // get list of additional databases used. Pass "this" (of type UserQuery)
    internal static List<string> GetAdditionalDatabaseNames(this UserQuery uq)
    {

        var props = uq.GetType().GetProperties();
        var result = new List<string>();
        foreach (var db in props.Where(
                               w => w.PropertyType.Name == "TypedDataContext").Distinct())
        {
            result.Add(db.Name);
        }
        return result;
    }
}

void Main()
{
    this.Connection.Database.Dump();
    this.GetAdditionalDatabaseNames().Dump();
}