2 or more Artillery in combined attack?

Hi, is it possible to do a combined attack with more than one artillery unit thus increasing the number of die rolled together even more than with one artillery unit? Thanks

If there is no rule in the rulebook, which limits this numbers (and i do not know such a rule), you can theoretical use 10 ART in a combined attack,
but i believe, the rulebook should be clear here, if you read it next time

Page 18, right column:
When an ordered infantry or cavalry unit is about to attack an
enemy unit in melee, one or more ordered artillery units may combine
their battle dice with the attacking unit......