Different logos for different activities

That is not possible in Dexxter. I used a separate invoicing system for my second activity for a while, but I eventually switched to one general logo. That saves me a lot of hassle.

Create invoices outside Dexxter (this also gives you more options for customising the layout), convert them to pDF format, sign them digitally with your eID or Itsme, and then upload them to Dexxter.