Why not just tether 20-25 thralls to food bowls (food bowls have decay timers) only allow food bowls to be placed within a certain range of one another the range will limit the number of thralls you have and if food bowls decay the thralls" run away".
Only allow 20-25 thralls to be placed in the radius of the food bowls. Food bowls would not need to be filled with food because you’re not just limiting the number of thralls but also removing them if the food bowl decays.
Food bowls with a cook T3-T4 could hold more thralls in the radius.
T1=5 thralls, T2=10 thralls, T3=15 thralls, T4=25 thralls,
Same mechanics for the pets with pet feed troughs but through and food bowls can overlap each other. The pet could be manned by an animal handler thrall.
Food placed in the food bowl and the through could be to help Health regeneration and the better food the faster healing the NPC gets.
AND make the purge specifically target food bowls and animal feed boxes