In what ways is China's newest population reform an example of another attempt at controlling the demographic make-up of the country?

 China has allowed some families to have 2 or more children. This will fix the gender imbalance and dependency ratio in hopes that there will be a younger population. There are plenty of elderly people that has nobody to take care of them since they're population is an aging population. I think this is a good idea to help the stop the gender imbalance and have a younger population, however, if the population growth rate increases, will China be able to support the people?