Toddler ride along step for Peg Perego Duette?

HI all,
A question from a lurker/occasional poster --
My mom asked me about getting a step for a toddler to ride, when she's
babysitting our nephew (age 2 3/4 years old) and our twin girls (8 1/2
months next week - wow). We have a Peg Perego Duette (an older model
with the large wheels), and so I'm wondering if anyone has any
experience with ride-along steps added to the back or front.
(Our other stroller is an older Graco Duo Glider - although I'm not sure
a step would work as well with that one since it's kept folded up
frequently).
My nephew is a bit of a rambler and is apt to wander off if my mom is
using both hands to steer the stroller.
any ideas?
Thanks
-Barbara