In the past year, Meng Yanyan, mother of a 5-year-old boy in Beijing, has made more than 20,000 yuan ($3,000) by selling her son's unwanted possessions.

In addition to online platforms such as Xianyu, Meng has found a closer, more convenient way to share secondhand children's items.

The young mom lives in Xiangshuwan, an estate in northwest Beijing that is home to more than 10,000 households.

The residents of this large neighborhood have organized their own WeChat groups, where they not only exchange information, but also swap secondhand children's items.

"It's a residential area, and very suitable for families with children. In the unit where I live, almost every family has more than one child," Meng said.

She added that she knows of at least five secondhand WeChat groups that each has about 500 members, the maximum number allowed.

Meng said dozens of people send information every day about their used items to the secondhand group she uses, often resulting in as many as 100 deals a day.

"English-language picture books are the most popular items. As soon as they are posted, they're gone," she said.

When the compound's service department discovered that parents frequently shared used items, it established "trading areas", where residents can leave items that have been bought so the buyer can pick them up without the hassle of finding a time to meet.

In the past year, Meng has even gained a "fan", a mother-of-two who lives in the neighboring area and whose second son is 6 months younger than Meng's boy.

"She really likes my taste and the condition of what I sell, so now when I advertise things used by my son, she buys most of them," Meng said.

After communicating online for a while, they have become more than seller and buyer, and they discuss raising children and other experiences. Meng learned that the woman is a space scientist, whose work is very busy. "She doesn't care much about appearance, and she believes secondhand products are environmentally friendly," Meng said.

She noted that many mothers in the residential area share secondhand goods to save money, but are more than willing to pay when it comes to tuition fees.

"A woman in the secondhand-sharing group pays 1,000 yuan per hour for her son to learn Go, a game played with black and white pieces on a board of 361 crosses, which requires great mental ability," Meng said.

In those WeChat groups, however, Meng sees different kinds of people: some may spend hours chatting to ascertain the condition of something they want to buy and ask for a lower price; some may post broken toys or dirty clothing; while others may even take other people's packages from the exchange shelf.

"So, when people with similar hobbies or personalities meet, they communicate more and even become friends," she said.

A mother who gave birth in the same hospital as Meng started a WeChat group called "Nobody Wants To Leave Once They Join", and Meng feels she fits the description perfectly.

The members discuss child-related questions and help each other.

When COVID-19 first broke out, many parents became anxious. The group leader made a list of hospitals that would accept children with fever and shared it with the group, Meng recalled. "It was a great help," she said.

Now, Meng checks messages in the WeChat groups almost every day soon after waking up. More than goods for sale, she finds a sense of belonging.