Hello Adrianbalzer
Max. 3xLT-330CL (=3x250 sheets + standard drawer 250 sheets) are possible.
With the MFC-L8900CDW + MFC-L9570CDW the larger additional trays LT-340CL (500 sheets) are also possible, but max. 2 pcs.
But to answer your question: I would not put the additional trays on top, but generally several are possible ;-)
Greetings