From supporters direct site (mostly paragraph 3 & 4 relevant).....
Reformed clubs vs New clubs
A critical issue to decide if you’re setting up a new club is whether the FA will consider your club to be a reformed club or a brand new one. If the latter, you’ll be placed at the lowest level of the senior pyramid where your club can safely be placed. That should be the bottom rung (Step 5 to Step 7) but with a lot of new clubs formed by trusts out of the ashes of their old club, their gates (and away following especially) are much greater than the level is traditionally used too. As a result, if the likelihood of placing a club in certain league is that fans and players safety will be jeopardised because the club they will play just are not capable of handling that size of crowd, then the club can be placed higher up the pyramid, at a suitable position.
Reformed clubs are judged to be essentially the continuation of a club in a new form – the club is dead, long live the club, so to speak! There is nothing set in stone as to what governs whether the FA view a club as a reformation, but several factors will be crucial. How long was it between the old club folding and the other club starting? Does the new club plan to play in the same community? Does it see itself as taking the same fanbase with it?
If the FA decides that a club is a reformation, then it must start at least two divisions lower than where the old club was at liquidation. The exact league will be a mixture of where places are available, where the club can safely be accommodated in terms of its likely supporter base and also whether there is a view that the reformation is the result of a club being liquidated deliberately to avoid or escape debts, or whether creditors have brought the action against a club.
With both of these, there are no hard and fast rules in place, so nothing should ever be assumed. The process of placing a club at any place in the senior pyramid is a function of the background as to why the trust has formed a club, the places available in the league covering that part of the country and the safety issues. For example, AFC Wimbledon started life in the Combined Counties Premier Division, but FC United and Scarborough Athletic started one level down from that in the North West Counties and Northern Counties East League second tiers respectively. Contrast that with AFC Telford; because they were viewed as a reformed successor to Telford United, they were placed in the Unibond first division, two divisions below where Telford were when they went into liquidation.
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So, essentially, we'd likely only take a 2 step drop as a true reformation. No way you'd want even a percentage of our fan base turning up much lower than that either way.