(German Freelancers) Saving Upwork Invoices + LexOffice

[seotexter]

I have a question for the freelancers living in Germany. 

I've a registered Einzelunternehmen, but unfortunately, I'm still waiting for my VAT number. Furthermore, I got a payment from Upwork without the VAT number included, so Upwork takes their percentage on VAT. 

My bookkeeping software is Lexoffice. 

So, a payment around €900 came into my bank account from different jobs. So, I got several invoices from Upwork (all adding up to that bank transfer of around €900). 

I'm confused about the invoices that I got from Upwork. Which one of those are important to save them into my "Belege" section in Lexoffice and show the payment of €900 for correct bookkeeping? 

I'm not sure if I've communicated my confusion correctly. Please ask if you didn't understand it.