We have four cats....and I know the feeling! A lot of it is trial and error, but the pouches you are giving them are very expensive. We vary our cats' food continually as they get bored easily. Try the Whiskas pouches (standard variety in jelly, not the Oh So Meaty as those are dear), or the Felix foil trays. What about tinned food? That tends to be better value. Kit e Kat or Arthurs are good value and not the cheap lines that smell 'dodgy'. Biscuits are good for their teeth, make sure there is water available though as they can get a bit thirsty. We tend to serve a mixture of Hills Science plan biscuits with Whiskas ones.
Hope this is of some help. Ali