So you could put an x-series chip in each location and not have issues with collision. However it really depends on your reader. One of those huge ones at parking garages would pick up everything and have issues, but your phone would be able to pickup each one individually. Then of course a flex has more range so I would count that has taking up the adjacent spots for an x-series implant.
Hope that all helps, if you wanted to install them all then my recommendation is position 0, 1, 2. If you have thick enough fingers maybe substitute a 6 or 7.