如何处理EF database first上下文列表并正确转换它们?

我有一个entity framework的6.0 database first上下文列表,这些上下文具有不同的名称。它们都包含一个名为“bill”的表。我需要签入每个数据库的账单表,并根据条件将信息添加到单个新数据库中。例子:

1. Company1_Entities
2. Company2_Entities
3. Company3_Entities

这3个数据库包含bill表。我需要将这些账单条件存储到:

All_Bills_Entities

随着公司数量的增长,我需要使其充满活力。我在想这样的事情:

Dictionary<string, DbContext> lstDB = new Dictionary<string, DbContext>();

// I'm supposed to retrieve these db names from a table, but now i'm just testing

lstDB.Add("00439837", new DbContext("Company1_Entities"));
lstDB.Add("00439832", new DbContext("Company2_Entities"));
lstDB.Add("00439839", new DbContext("Company3_Entities"));

using (All_Bills_Entities main_db = new All_Bills_Entities())
{
    foreach(var dataBaseInfo in lstDB)
    {
        DbContext currentDB = dataBaseInfo.Value;

        foreach (var record in currentDB.bill.ToList()) // this does not compile, there is no bill table found here
        {
           if(record.merchant == dataBaseInfo.Key /* && other Conditions */)
           {
                main_db.bill.Add(record)
           }
        }
    }
}