Tiling over missing tile

[Domboy77]

I am beginning work on my bathroom and will be tiling over the floor tiles rather than removing them. The issue is have is that one of the tiles was broken and was removed. If I am tiling over the existing tiles what should I do about the missing tile. Do I replace or fill first? Or do I just use more adhesive where the missing tile is?

Thanks in advance

[royaloakcarpentry]

I wouldn't tile over tile, so can't advise.