In a large pot over medium heat, add chicken stock and bring to a boil. Submerge bihon into the liquid and cook, using tongs to loosen strands, for about 1 minute or just until softened. Drain noodles and reserve about 2 cups of broth.
In a wok or wide pan over medium heat, heat about 1 tablespoon oil. Add shrimp and cook for about 1 to 2 minutes or until color changes to pink. Remove from heat and drain on paper towels. Set aside.
Wipe down the pan and add more oil as needed. Add fish balls and cook, until lightly browned. Remove from heat and drain on paper towels. Set aside.
Add onions and garlic and cook until softened.
Add chicken and cook, stirring regularly, for about 3 to 5 minutes or until lightly browned.
Add carrots and cook for about 1 minute.
Add cabbage and cook for another 1 minute.
Return shrimp and fish balls to skillet. Continue to cook until vegetables are tender yet crisp. Remove from heat and set aside.
In the skillet, add reserved 2 cups broth and kecap manis. Stir until combined and bring to a boil.
Add miki noodles and gently push down into the broth. Cook for about 1 to 2 minutes or until softened.
Add bihon noodles and vegetable mixture. Season with salt and pepper to taste.
Continue to cook, stirring regularly, for about 3 to 5 minutes or until noodles are cooked but firm to bite, vegetables are tender yet crisp, and liquid is absorbed.
Transfer to a serving platter and garnish with green onions and calamansi. Serve hot.