Good Morning!
I wanted to develop my headcanons for them a bit more. Previous info installments can be found Here and Here.

As the foals of Ponyville grew up, many of them stayed behind and decided to settle down back at home. Some of these foals knew that they were going to stay in Ponyville forever. Some of these ponies were Applebloom and Sweetie Belle, for example. Others had plans to go and be successful. Diamond Tiara was going to become a strong politician. Silver Spoon was going to become wealthy up in Canterlot. And Snails, well he didn't really have a plan. 
However, things always don't go as planned. Around the age of 18, Diamond Tiara and Snails were dating and going steady. Silver Spoon was still Diamond's best friend, even if Silver wanted to be more with her. One day Diamond Tiara found herself unexpectedly pregnant with Snail's foal. She confided in Silver Spoon and they told Snails together. While it was shocking for all, it also meant the girls couldn't live their dreams quite yet. 
As time went on as they awaited the arrival of the foal, Silver Spoon ended up confessing to Diamond. Feeling incredibly conflicted, Diamond Tiara thought of an idea. She loved both Snails and Silver very much and the two seemed to be quite close as well. Thus, the three formed a polyamorous relationship. Not long after they started dating did they get married, and soon enough their little filly Spice was born. 
By this point their dreams had changed. Instead of getting big in Canterlot they all wanted to stay in Ponyville and raise their family. That meant their careers had to shift as well. 
Instead of being a famous politician, Diamond Tiara became the mayor of Ponyville once Mayor Mare finally retired. 
Silver Spoon indulged in her fancy fantasies by opening up her own jewelry store where she sells accessories and even fine cutlery.  
And Snails finally found his calling. Miss Cheerilee was getting up in her years a bit and needed an extra hoof. Snails decided to volunteer to give him something do to and he ended up loving it. More importantly, he loved teaching and assisting fillies and colts who weren't neurotypical, struggled a bit more than others, or just needed help in a certain area. Growing up Snails wasn't the brightest. Things just didn't connect in his brain very well. This resulted in him being held back a year or two. If it weren't for Snips coming along who knows how sad and lonely he would've been. Not ever wanting another foal to feel his pain, Snails devoted his life to making them feel welcome. 
After a few years of only having Spice, the partners wanted another baby wandering around. Thanks to evolved magic discovered by Twilight Sparkle, Diamond Tiara and Silver Spoon were able to biologically have their own. That's how little Sugar popped into the world. Sugar and Spice are incredibly close, the ideal image of sisterhood. 
And of course they all stayed in touch with Snips and Twist a ton! The two families are basically related and refer to each other as aunt/uncle and cousin. The Diasilsnail family is also in touch with Applebloom's family quite a bit after Applebloom helped Diamond Tiara with her first pregnancy, relating to the mare quite a bit since her first daughter was born a year before. 

That took me around 20 minutes to type. Wow.

Diamond Tiara and Silver Spoon Base by :iconelementbases:

Snails Base by :iconselenaede: