After exactly 10 minutes of thinking, I thought of who was the Captain of the Guard before our Cap and Lance's mom.
Her name is Alanza Schnitz. She's very loud and boastful, but also very honorable and heroic. She has a strong sense of justice and does everything in her power to do what's right for her kingdom.
During her time as Captain, she briefly fell in love with a man who was a bit of a sleaze but was good at hiding it. When she told him she was pregnant, he dipped. And poor Alanza was scared about having to choose between her baby and the kingdom. In a brief moment of cowardice, she named her son Arnwaldo, and quickly travelled to Vardaros to give him to the orphanage.
Not long after that, she became Cap's mentor. She taught him everything she knew. She even sent him out personally to go after Gothel when she kidnapped Rapunzel while she stayed to calm Arianna and Frederic down and look for clues. She wanted to lead the search parties, but Frederic instead demanded that she leave that to Casper while she patrolled the city more. And thus...the crackdown on crime began. At first she tried to go along with it, but soon it just felt more and more disgusting. After a couple years and the execution of Caine's father, she finally decided to quit. Naturally, she made our Cap her successor. Despite quitting, she still stayed in Cap's life, and Cassandra's as well. She was actually the closest thing Cass had to a grandma.
As for Lance...she suspected that Flynn Rider's infamous sidekick was her son for a long time, but she never tried to contact him because she was too afraid. Eventually, at some point after the show, she finally faces her fears and reunites with her son.