Can I attatch new fence to neighbours concrete posts (not their fence panels)

If the concrete posts belong to your neighbour then no... maybe just bite the bullet and replace the fence panels... hope this helps

If the fence posts belong to your neighbour, then not without their permission. It may be better to just erect a new fence in front of theirs, within your property boundary.

Hello Courtney, If it is impossible for your neighbour to understand the situation, then your best option is to build your own fence within your boundary. I hope everything will go well for you.

The best solution if there’s no way of sorting the fence between you and he has paid for fence and post is to do your own fence in front of his with the good side facing you if you drill into post and burst it it could cause more trouble the fence is a boundary line unless it is clearly on his side of the land

This is one option but this is also tricky. On your deeds it will give you the exact boundary lines. If the fence is on his side you cannot do anything to the fence, even change the panels without their permission. HOWEVER if the fence is on your property you can asked them to move it so that the posts are situated on the boundary line or replace the panels..... you are allowed to do anything on your side of the boundary line. I would install a new fence line inside the existing fence. Be sure to put a string line up and put the post positions half way between theirs. This is so you will not interfere with their posts in anyway and cannot be blamed if their posts move overtime.

If the fence belongs to them and they can be awkward about stuff, I wouldn't bother Attaching anything. The best way is to put another Fence as close as possible. As gmbs has said put your posts in between theirs so your not doing any damage.

I personally did that in my garden, this was because my neighbour told me he would get it done and never has, my daughter kept falling down the gravel strip as the panels had bowed, dropped and left a void. I Simply anchored 3x2 rails to the concrete posts and feather edged the run. Maybe the best option for yourself would be to ask your neighbour before you do it :)