Livingston and Fell have been in great form this year
Britain's Katy Livingston won a bronze medal at the Modern Pentathlon World Championships in Budapest to virtually secure her place at the Olympics.
Heather Fell was fourth to help the team of Livingston, Fell, Mhairi Spence and Georgina Harland to a silver medal.
Livingston and Fell had already reached the Beijing qualifying standard and should both have Olympic medal chances.
GB won a second silver when Livingston, Fell and Mhairi Spence came second behind Hungary in the team relay.
Sam Weale, who finished 25th in the men's final on Sunday, faces an anxious wait to discover if he has qualified.
But team-mates Nick Woodbridge and Ben McLean failed to progress from their semi-finals and can no longer reach the Games.
Performance director Jan Bartu said: "It was fantastic to win an individual bronze and a team silver.
"This is a new generation of young athletes taking on the best in the world and we are very, very proud of them.
"Katy was very nervous at the start of the shooting phase, but she fought back and fenced fantastically. She produced a very high quality performance."
Since women's modern pentathlon - which combines fencing, swimming, shooting, riding and running - was introduced to the Olympics at Sydney, British athletes have taken half of the medals on offer.
Steph Cook won gold and Kate Allenby took bronze in 2000, to which Georgina Harland added bronze in 2004.
Harland needed to finish on the podium above both Livingston and Fell to reach Beijing but is now set to miss out.
Weale's Olympic fate rests on international rankings following his appearance in the men's final.
"I'd be devastated if he didn't get to the Games," said Bartu. "He's worked hard this year and I think he deserves his place.
"I don't think it's the end of it for him. We now have to wait until the qualification list is published to see where we are."