gistfile1.cs

public class EditMasterQuery
{
  private readonly IDocumentSession _session;
  public EditMasterQuery(IDocumentSession session)
  {
    _session = session;
  }
  
  public MasterWithSubdocs Execute(string masterId)
  {
    var master = _session.Load(masterId);
    if (master == null)
      return null;
    var scope = master.Scope;
    var subdocs = _session.Query<SubDocuments>()
      .Where(/* subdoc matches scope */)
      .ToList();
    return new MasterWithSubdocs(Master = master, SubDocs = subdocs);
  }
}

public class AssembleMasterQuery
{
  private readonly IDocumentSession _session;
  public AssembleMasterQuery(IDocumentSession session)
  {
    _session = session;
  }
  
  public MasterWithSubdocs Execute(string masterId)
  {
    var master = _session.Include<Master>(m => m.SubDocIds).Load(masterId);
    var subdocs = _session.Load<SubDoc>(master.SubDocIds);
    return new MasterWithSubdocs(Master = master, SubDocs = subdocs);
  }
}