I’m uncomfortable with my boastful sister-in-law

My sister-in-law, who is of the same age as me, married my husband’s older brother five months prior to our own wedding. Both our families reside far from home and occasionally return to our in-laws’ hometown.

She and my brother-in-law have a son who is three years old, whereas my husband and I are parents to a one-year-old daughter. Our interactions were once filled with enjoyable conversations. Over time, however, I began to notice my sister-in-law’s tendency to boast, which I find discomforting.

Her conversations frequently center around her son, as she narrates various anecdotes and lavishes praise upon him. She has a habit of interrupting me while I speak of my own child, to highlight her son’s achievements and draw comparisons between the two.

For instance, she boasts that her son began to roll over at three months, managed to crawl by six months, and was walking by nine months. Yet, in the presence of our mother-in-law, her story changes, claiming he rolled over at four months, crawled at nine months, and walked at a year old. The latter account, validated by my mother-in-law’s frequent interactions with my nephew, is accurate.

During one of our conversations, my mother-in-law mentioned that my nephew was still breastfeeding at 20 months. Contrarily, my sister-in-law claimed the following week that he had been weaned off for several months.

She once alarmed me by stating her son had a high fever of 40-41 degrees Celsius one afternoon; however, upon my visit that evening, he appeared perfectly healthy, engaged in eating and playing. Yet, a few days later, she informed our mother-in-law that her son had been unwell for three weeks before making a recovery.

Also, she frequently draws comparisons between her son and my daughter in an attempt to prove her son’s superiority.

While my family has not yet acquired a car or house, my husband has opted for a rented self-driving car for our convenience since my pregnancy, facilitating our visits to his hometown. My sister-in-law often requests rides, citing her child as justification, which results in additional hours of travel for us due to her residence being in a different direction.

These issues, albeit minor, have been dismissed by my husband upon discussion. Yet, I remain uneasy.

Should I overlook these concerns as well and endeavor to enhance my rapport with her?