You need ATC to decide the 'batting order' when more than one aircraft at a time requests the iap. There may be a 'need' to allocate different altitudes to the first and second aircraft. This is called 'separation' and as such can only be applied by ATC, not FIS.
Course if you're not flying for PT, there's nothing to stop you designing your own 'private' procedure as mentioned above, but I'm not sure what attitude your insurance company might take to doing this. Correctly designed with a 'bulletproof' missed approach procedure (which most private procedures don't appear to have) then you could ask them. Most self designers seem to be unaware that the minima you use needs to take into account any high obstacles in the 'missed approach area'.