Thanks for all the well wishes!
Does this ever happen in Jewish families. Four kids and the youngest is first to get engaged (girl)?
With caveat that there are a lot of differences between communities;
Being that most people within a specific community get married in a specific age range (for example girls between 19-21 and boys 22-24) it is uncommon for a younger sibling to get married before an older sibling of tye same gender. However, girls will often get married before an older brother.
The reason
@Yammer called it "unfortunate" is because when it does happen, it is often because the older sibling has been trying to find a match unsuccessfully for an extended period of time.