The ability to split signed documents from one pdf to multiple pdf's?

We send multiple invoices for signing to our controllers every day.

When we send this in one pdf we get it back also in one pdf which is great, but we would like the ability to then split the pdf into multiple pdf's as it contains seperate invoices.

My question is, is this option available and how can I enable it?

(we can also just send one pdf for one invoice, but then our controller gets 20 emails per day for just signing which is simply not practicle)