Feeding Toddlers in a highchair is impossible...

[Whytry]

They just keep doing random things when im trying to get them to feed the baby.. like for example putting food on the high chair then moving the food to a different highchair and putting the kid in the highchair with no food.. then keeps taking the kid out of the highchair when i try and move the food.. THEN randomly EATS THE FOOD

[daveyd]

Put the food on the ground like the way you feed your dog, that's how the sims 4 'works', it's bass-ackwards. I personally never used the high chair for toddlers after watching Carl's Sim4 'guides' on you-tube.

[Xautos]

Highchairs at first help your toddler out, but after eating and a little conversation with the babbling child, the toddler is likely to feel trapped in the highchair and will want to be let out. So if you do use the highchair, make sure you are attentive to your toddler sims needs and get them out of the highchair as soon as they finished eating, cleaning up and then watching what they are doing.

The alternative is to create a walled off area sort of like a mega playpen where your toddler can spend all their time having this one area to wonder around, play, sleep and eat in, if you set it up right, the toddler won't need for anything, just as long as your adult sim is there to keep their social need up and keep them from doing bad thing such as making a mess and getting into a tantrum which creates tense moodlets for your adult sims.