Investors & landlords

Instead of entering individual stock sales, I have decided to use the summary method as mentioned and mail the 1099-B with my Tax Return.  However, here is another problem.  If you have multiple brokerage accounts, the wash sales losses that are disallowed need to be reconciled manually across all brokerage accounts to arrive at an accurate cost basis.  How do we do this when there are 100's of transactions spread across multiple brokerage accounts?