Currently handrail extensions are controlled in the handrail type properties, so create the same handrail with a different extensions users have to create a new handrail type.
It would be great to set the default extensions in the type properties and then un-pin the handrail extension and switch them between floor/wall/post, plus tread depth, etc and control the sketch line accordingly for each handrail instance. This would reduce the number of handrail families to manage and make extensions faster/easier to modify. 