hi I'd like to know the best way to securely install fence posts when erecting a fence between gardens of different heights. The gardens slope down fairly significantly and so both our garden and our neighbours are terraced but theirs is about 30cm lower than ours in some places and 15 - 20cm in others. We get on well so access to their garden shouldn't be a problem. The current fence is falling down where the posts have no support. It's on our boundary so the posts would need to be in our garden as far as I know. We're going to reuse the 5ft wooden fence panels but i imagine we'll need to buy new posts and fixings. Do we just need extra long posts and then dig down below the level of their garden and concrete the posts in or is there another way? Any suggestions would be greatly appreciated. Thanks.