The main thing female lovebirds need when they are laying eggs is calcium, so feed them high calcium foods like hard-boiled egg and maybe some spinach. I used to give my birds this supplement powder called egg-cite that had honey and egg in it. Most breeder supplement mixes have vitamins birds need when they have babies, so one of those might be worth trying. About the vegetables-- my birds never ate anything besides seeds and pellets, so I don't have much experience with this. You might give them like two or three small servings of vegetables per day.
What kind of diet do you do? How many times do you feed them with vegetables? What else do you give aside from seeds and vegetables? Gratitude to future response(s).