I am replacing a run of 12 x6' bays. The first and last posts are in fixed positions being against the house and at the convergence of boundaries. Ideally I would like to erect the new posts in the same position as the old. However I would have to remove the old concrete first which would be very hard work or I could dig new holes next to the old which would result in the bays being approx 7' which would then concertina along the run with the last bay being only 5' or so. Due to neighbours I can't dig new holes either side of the old, only in the direction of the run. Any ideas much appreciated.