Well, I don't get exactly what your saying, but if I understand relatively correctly then you are looking to make an update that uses multiple bounding boxes. To do this create either a list of AxisAlignedBB objects or just another AABB field. Then, create an void onUpdate or onEntityUpdate function in the entity's class and in that do super.onEntityUpdate() or super.onUpdate() and then do something like this
List<Entity> ents = worldObj.getEntitiesWithinAABBExcludingEntity(this, boundingBox);
ents.addAll(worldObj.getEntitiesWithinAABBExcludingEntity(this, boundingBox2));
or
List<Entity> ents = worldObj.getEntitiesWithinAABBExcludingEntity(this, boundingBox);
for(AxisAlignedBB bbox : listOfAABBs) {
ents.addAll(worldObj.getEntitiesWithinAABBExcludingEntity(this, bbox);
}
EDIT: never mind my last part, it is useless for this task (I'm not sure your explaining what you want right) if you wanted to mess with AABBs, this would work.