One Job many export invoices... How?

We needed to divide a big big warehouse to export.
As we wanted to have only one job, we use co-parts, because we think that making various releases for one line, it will not work.
But in the way we used the co-parts it didn’t work either
Finaly in accounting, it looks like we lost money.
So, How can we do several packin slip with their respective invoices for a project, if we can´t specify the final price and the final weight of the product, but we need to send it in parts?

Neither we can divide 1 pz in, for example .25 because the american bridge doesn´t allawed