Cancelled Draft Invoice Links to EI's

When I cancel an invoice, the line details delink from pa_cust_rev_dist_lines_all.  The cancellation invoice subsequently also does nto ahve a link to these items in this table.  I need to be able for both the original invoice and cancellation invoice get to the EI details so that I can write a program that will pick this up; can someone guide me how I can do this?

Example

Proj1

Inv 1

I cancel Inv 1 and now have

Cancellation Inv 2

I need to be able to write a query to get to the EI for both Inv 1 and Inv 2