Parents-in-law feeding my child with same spoon and chopsticks is unsettling to me

For the past three years since my marriage, I’ve been dealing with this issue, and our nearly two-year-old child has become the center of an unusual cultural clash. My in-laws, despite coming from urban backgrounds, exhibit peculiar habits that starkly contrast with the rural customs of my own family. The habit that disturbs me the most involves my parents-in-law’ tendency to moisten and lick the spoon and chopsticks prior to feeding my child.

Normally, I am responsible for preparing porridge for our child, but on occasions when my work causes me to return home late, the task falls to my mother-in-law. She has a habit of tasting the porridge directly from the cooking chopsticks multiple times during preparation, only to return them to the pot for stirring.

I have proposed using a separate bowl for tasting to avoid this, yet she dismisses the idea, asking: "Why make it so complicated, then we have to wash an extra bowl and spoon?"

The bond between my child and his grandfather is strong, to the point where my child prefers eating only when fed by him. However, my father-in-law has a habit of pre-chewing the rice before feeding it to my child, out of concern that the child may struggle to eat it otherwise. This behavior is something I find hard to watch.

Moreover, he frequently samples the porridge to ensure it is not too hot for the child, ignoring my requests to cease this practice. Each time I express my concerns, he briefly shows discontent before resuming his preferred method the following day.

The idea of enrolling my child in daycare early was a consideration of mine, however, the baby's frequent illnesses have made my husband and in-laws opposed to this option.

At this point, I’m unsure how to convince my in-laws to change their caregiving practices for my child. Do you have any advice?