feather board fencing

[Clive]

I want to increase the height of my current feather board fence from 3'6" to 5'. I have 3ft concrete posts holding up the fence. I want to replace the feather board fencing but keep the posts. This gives me some challenges
1) will the posts hold the weight of the increased height fencing?
2) Will the fencing be sturdy enough at the top without a post to hold it in place?
3) How do i fill the gap between the feather boards where the posts will be?
I'm sure there will be other questions as the project moves on but any suggestions would be appreciated

[thedoctor]

Featherboard fencing gets its strength from the struts between the posts and if you just extend the boards up beyond the post height there is no strength at all. Forget the posts you have and insert new posts, at the correct height, in the gap between the old posts. You can then cut or breal the old posts down. To try and remove them, as they are no doubt concreted in, is a really difficult job, so just break them down and cut the steel. You can then add some earth and turf over them.

[Clive]

Many thanks - not the answer I wanted as it will cause me a lot of back ache - but I'll take the experts advice