Thanks for taking these guys in. For now, don't stop feeding them the seeds and only give them veggies, that's not going to be good for them, they need a "staple" food that they get daily, and for smaller birds like Lovebirds, this is going to need to include a seed-mix, but a healthy seed-mix that contains NO sunflower seeds, as they are nothing but fat. What you want to do is try to incorporate a small-size pellet into their diet, and have this eventually be the main "staple" to their diet, and then they should also get a healthy seed-mix with no sunflower seeds in it as well as the pellets. As for fresh veggies, you can give them any veggies except for onions, as they are toxic to birds. And the veggies have to be fresh, no canned...Anything from different Bell Peppers, Broccoli, different Squash, Green Beans, Pea Pods, Sweet Potatoes, Yams, Eggplant, Carrots, etc., as well as dark, leafy greens. Lovebirds usually like their fresh veggies cut into very small pieces that will easily fit into their beaks, so try different fresh veggies and different ways of cutting them.
For now, they should always have a healthy, low-fat seed-mix that is appropriate size for Lovebirds in their cage (again, no sunflower seeds or nuts), along with always having fresh water. You need to fill their seed-mix dish every single day, as well as their water dish, and check their water throughout the day to make sure it's clean and full. As for the fresh veggies, you can offer them to them each day, throughout the day. What you want to give them sparingly are fresh fruits, maybe only a small portion of fresh fruits 3-4 times a week, as they are full of sugar. But the fresh veggies are fine to give them every day, and in larger portions. Just make sure that they always have seeds in their bowl for now, as this will be their "staple" food/diet. (Never feed your birds any Avocado, as it's toxic, nor any Citrus Fruit like oranges, lemons, limes, grapefruit, etc., as it can cause them to absorb too much iron and cause Iron Absorption Syndrome, and then again, no onions).
What you want to do gradually over time is to switch their main "staple" diet from being just a healthy seed-mix, to a mix of small-size parrot pellets with a healthy seed-mix as a smaller portion/supplement to the pellets every day. But you can't just stop the seeds and give them pellets, as usually they won't eat them right away, you have to slowly incorporate the pellets into their seed-mix, and slowly reduce the amount of seeds they get, making sure that they are actually eating a good amount of the pellets. There is a great guide on here written by Harrison's Pellets with a step-by-step guide on transitioning birds from seeds to pellets.
As for catching the male, leave his cage door open, and make sure there are seeds and water inside his cage, he may get hungry and go back in the cage...But as far as catching him, you can try using a towel to throw over him and then gently grabbing him and putting him back in the cage...You may want to consider clipping their wings, just the outermost 4-5 primary flight feathers on each wing, no more, as this will give you a good month and a half to two months to be able to work with them one-on-one without having to chase them, etc. They'll be able to fly again in about a month and a half to two months, and by then hopefully you'll have formed a bit of a bond with them, and they'll be much easier to train.
A lot of people are going to get hostile about clipping their wings, but this is a very personal decision that only you can make for your birds. And I'm not at all talking about keeping them permanently clipped or clipping them dramatically, I'm only talking about clipping the outermost 4-5 primary flight-feathers on each wing, and then letting them grow in over the next month and a half to two months, during which you'll be much more able to interact with them, earn their trust, and tame them. Then once their wings grow back in you should let them be fully-flighted from that point on. A lot of people find this a much more manageable way to work-with/train/tame non-tame parrots when they first bring them home...The worst thing you can do when you get new birds that are not tame to begin with is to have to constantly chase them around your house with a towel or a net, you'll never earn their trust or tame them that way, so doing a slight, temporary wing-clip on them is a great way to solve the out-of-cage issue. And they will have to rely upon you while they're clipped to get around and such, so this strengthens the bond between you with them, and you do tend to earn their trust this way quickly. I've hand-tamed many non-tame Budgies this way, and I've only ever had to clip them that one time, when I first get them, work with them daily during that time period when they can't fly, and then that's it. It doesn't hurt them or cause them a bit of pain, and it's very temporary. You do want to get it done by a professional, either a Certified Avian Vet or Avian Specialist Vet (wellness exam ASAP for both of them is a great idea anyway), a local breeder, or even a bird shop or pet shop that has a bird-person working there that knows the proper way to clip wings...And make sure if you do this that you tell them you ONLY want their outermost 4-5 primary flight-feathers clipped on BOTH wings, no more. And never only clip one wing, we've had a bunch of that this week, and it's very unsafe and bad for the bird's back.
He's with Lovey now, and they are eating millet. 
