public IQueryable<Client> GetTopLevelData(Guid agentGuid, int year)
{
    var clients =
        from client in ObjectContext.Clients
        join cbc in ObjectContext.Client_Bucket_Client on client.Client_GUID equals cbc.Client_GUID
        join acb in ObjectContext.Agent_Client_Bucket on cbc.Client_Bucket_GUID equals acb.Client_Bucket_GUID
        where acb.Agent_GUID == agentGuid
        select client;

    var clientInfos =
        from c in clients
        select new
        {
            Client = c,
            TransactionInfos = ObjectContext.Transactions
                .Where(t => t.Client_GUID == c.Client_GUID && t.Year == year)
                .Select(t => new
                {
                    Transaction = t,
                    ToAttach = ObjectContext.Forms.Where(f => f.Transaction_GUID == t.Transaction_GUID && f.Year == year) //.OrderByDescending(fo => fo.Create_Date)
                })
        };

    // Looping over this query will hit the database *once*
    foreach (var info in clientInfos)
    {
        foreach (var transactionInfo in info.TransactionInfos)
            transactionInfo.Transaction.Forms.Attach(transactionInfo.ToAttach);

        info.Client.Transactions.Attach(info.TransactionInfos.Select(t => t.Transaction));
    }

    // Return a queryable object; constructing a new query from this will hit the database one more time
    return clients;
}