Lived in this house 35 years. Now wife needs a handrail to get up/down
front steps. Planning on going with metal railing, 36" high.. Posts are 2x2
with a square bottom flange with four holes for bolts. The manufacturer
recommends 3/8" x 4" expansion anchors for attaching posts to the concrete
steps.

The problem: A few years ago I overlaid the steps and sidewalk with
decorative concrete "stones" which are 11 x 14 x 3 1/2" thick. Two layers.
So, the concrete steps are 7" below the surface of the stones. The stones
are held in place with construction adhesive, which has been satisfactory so
far. But definitely will not hold the stones securely enough to support a
handrail. I could use 12" long expansion anchors to penetrate to the
concrete steps but they are 3/4" diameter and I'm concerned about the "swiss
cheese" effect on the concrete. Alternately, I could use 5/8" x 10" anchors
with only 3" in the step concrete, which would probably have enough holding
power and slightly less "swiss cheese".

What are the other options for securing the posts, if any? I would be
especially interested the approach others have successfully used in a
similar situation.