Y’know what they say. If you can’t get the man, go for his brother.
 
Pinkie Pie had little to do with Trenderhoof during his first visit to Ponyville. She simply humored Rarity’s ramblings of how handsome he was an how stylish. She had heard it before, but remained always positive. Maybe they’d get together? Maybe he wouldn’t be like Prince Blueblood? Despite Pinkie’s air-headed-ness, she wasn’t completely unaware of the things around her.
 
After Cheese left, Pinkie knew already that Cheese and Pinkie could not be together. Despite Pinkie’s optimism, she knew that Cheese only looked up to her, and had nothing romantic towards her at all. Pinkie did feel attraction towards him, but knew it was not meant to be. Especially when Cheese re-visited and began chatting it up with Applejack. She felt happy for her maybe-cousin.
 
Luckily a day later Trenderhoof came back to see his brother, Cheese, whom Pinkie did not know they were related. Now it was obvious to see. They each (at least at one time) wore glasses, similar brown coat, similar height. She guessed Cheese left Manehattan, but Trenderhoof didn’t. She soon got caught up in Trenderhoof during dinner at the Apple Orchard, explaining away most of her life story and her most recent escapades. Trender was surprised to hear that Pinkie could be related to Applejack.
 
For whatever reason, Trender found her relation to Applejack so compelling he began calling up favors of historians to research bloodlines. It was true, Applejack and Pinkie Pie were related, and to thank Trend for finally confirming this Pinkie Pie gave him a peck on the cheek.
 
That peck escalated things as they began to become even closer. Pinkie Pie was happy enough to oblige in the expensive private dinner dates, the boat rides, and more. Trenderhoof admired Pinkie’s enthusiasm and was willing to tolerate her hyperactivity.
 
Their wedding was very expensive and incredibly grandeur, entirely set up in Manehattan. Almost all of Ponyville came to the wedding to celebrate, along with many of Manehattan’s elite by social requirement. The party lasted almost the entire weekend, when the festivities were finally stopped when Princess Twilight politely asked for the party-goers to go home due to the traffic they caused.
 
They wasted no time have a child.
 
Trender and Pinkie argued over a name for several days before finally agreeing up Private Party. It seemed Party picked up many of his father’s characteristics while keeping all of Pinkie’s energy. He’s extremely kind, but also somewhat posh. He’s extremely interested in the country but finds getting dirty to be uncouth. He’s often embarressed of his mother’s antics, since she does not behave like other Manehattanites do. He’s very talented with throwing private get-togethers with the Manehattan elite, and is great at entertainment.
 
As he grows older, he will construct a club near the center of Manehattan called the Shimmy Changa (geddit?) and has a whole line of clubs being constructed in other cities and even other countries.