In order to join your family or relative in Sweden, you must have a residence permit. Citizens of Moldova can apply online or in person at the Swedish Embassy in Bucharest. The Embassy in Chisinau does not handle visa applications
You can find details on how to apply for residence permits for yourself and/or on behalf of your child at the website of the Swedish Migration Board.
The quickest and easiest way to apply for a residence permit is to apply online over the Internet. An online application goes directly to the Swedish Migration Board and is given priority. The Board aims to reach a decision within four months.
If you cannot or do not want to apply online, you can submit an application document in person to the Swedish Embassy in Bucharest. You need to make an appointment.
More information can be found on the page of the Swedish Embassy in Bucharest here.