Are you talking real blueberries or huckleberries which are a much larger bush that would compete with the tree for space? (2' and tiny seeds for blueberry and 6' and larger seeds for huckleberry.)
People from your area of the country tend use the names interchangeably or they simply always call the area native huckleberry, blueberry.

If blueberries, IMO that would be the wisest place to plant them. Under the canopy of trees is where they naturally grow and they're small enough to not cause any problems.
Although they grow in the north woods and like an acid soil which I don't know if the pears would like.

I won't plant them there unless you have no other spot. That's not much space for even one other plant. And those pears will get bigger, maybe even nearly fill in the 10 ft space.

The Fruitnut

Thanks for the follow-ups.
The Asian pears are on dwarf rootstock, and the blueberries would be real blueberries, like the ones I have now, which are 25 years old and only about 5 feet tall.

How do you plan on 5 feet of plant fitting where you have 0 feet of space?
The rule of thumb is that dwarf trees get 10' tall and 10' diameter.

I would plant a lowbush to make use of the space blow your limbs, but once your trees get full size they will be touching each other so a highbush is out of the question.