I plan to add insulation to my attic. Right now I have R11 fiberglass bats
between the 2x4 floor joists. On top of the joists are 2x8 sheets of
plywood (not secured to the floor) so we can store things in the attic and
to make sure we don't step through the ceiling underneath. Should I remove
the plywood before I put down the addition bats of insulation, i.e. so the
old fiberglass is touching the new? Or can I just put the new insulation on
top off the plywood?

Thanks,