While printing via the DocuWare Printer PS, it's not possible by default to choose a tray on the MFP for redirected prints.
Edit the following PPD file in the folder: "C:\Windows\System32\spool\drivers\x64\3\bzpdf87.PPD" and copy the following line at the end of the file:
*InputSlot Tray1/Tray 1: ""
Afterwards restart the print spooler via the Microsoft "services" window. In this example, the tray 1 will be used for the further printing to a MFP device.