It's easy to locate excluded invoices/bills in the 'Invoices Due' and 'Bills to Pay' sections as these will display an excluded tag.

If none of the excluded invoices/bills are showing you just need to tick the 'Display excluded invoices' option and these should then show in the table.

Excluded invoices/bills can be re-added from the 'Invoices Due' and 'Bills to Pay' section at any point, by clicking the toggle at the end of a row, or clicking into the invoice/bill and re-ticking the 'Include in cash flow' option.

If multiple invoices/bills need to be included or excluded these can be updated in bulk.

Go to the 'Invoices Due' or 'Bills to Pay section' depending on whether you are looking for invoices or bills.

Next, select the invoices you would like to include in the cash flow using the check boxes shown to the left of each invoice. Note, only invoices that are currently excluded will be affected by the include option. 

Now using the 'Batch actions' shown at the top left of the table you can choose to 'Include in cash flow' which will set the selected invoices from excluded to included.

If you would like to exclude a number of invoices/bills in one go you can follow the same process by selecting the relevant invoices/bills and choosing 'Exclude from cash flow' from the 'Batch actions'.