No big deal.....
Theortically you can increae the amount of active dry in relation to
instant yeaat by 25-30% but in actual practice bakers don't care much
about the quantity and would use the same amount. as long as you know
how to handle each yeast type according to pack directions.

Keep in mind that the main, difference between the active dry and the
instant dry is the word instant and active.<grin>