Well, frozen
BABY brine shrimp are fine, just by themselves for the fry. I feed those for the first 10 days or so - exclusively. I just drop a cube into a little cup, add a touch of water until they thaw and pour the tiny specks of food over the tank. The fry will gobble it - most get it all before it even reaches the bottom of the tank.
Remember - fry are TINY. They need food that is quick and easy and filling. They are not as willing to sit and pick at the gel food as they probably should be - at least at first. Having a piece of gel food in the tank during the day to give them the option to graze all day is great - but I do not feel it is enough. Having a nice plush layer of green algae will do the same thing - the fry will graze all day long.
Bloodworms and brineshrimp ( not baby) and even frozen daphnia is really too big for new fry (under 10 days) Stick to the baby brine shrimp or egg yolk. After about 10-14 days, you can branch out to the daphnia (I buy mine frozen and dissolve them and feed the the same way as the frozen baby brine shrimp) If the fry are fed well, within about 14-21 days, they are ready for the regular SanFran frozen brine shrimp. These, too, can simply be thawed and distributed about the tank. They enjoy a cube of gel food (veggies only is fine if you are feeding shrimp for other meals). Daphnia and baby brine shrimp are too small - and most fry will not mess with them. That is the time to soak some crushed flakes or pellets of standard food so that they sink, and feed them for one meal. I have 9 different foods for the fry - all but the brine shrimp are ones that I use for the adult fish, just in smaller bites.
I feed the fry a wide variety of things. I try to have gel food of one nature or another available during the day. I have algae on the back walls. Do not count on one food alone to do the job. Definately do not count on gel food to do the whole job for you. Bloodworms will need to be chopped very very finely for fry to eat - and if not eaten, can foul the water. So chop them carefully - or wait until the fry are bigger. Mine do not get them - I give them to the adults. Crush the flakes and soak them. Crush the pellets and soak them.
Brine shrimp (frozen types) do not have to be cooked. In fact - do not cook them. They are best eaten "on the hoof" - live if possible. The krill and such - cook them if you wish (I am assuming you are buying the ones from the butcher shop that you would eat, right?) That is fine.
The cat will enjoy any of the foods you make. Mine love to clean out the fish's feeding bowls after I have fed. They lick out all the drips of shrimp and fish.... YUM!
I am glad your grandma is doing what a grandma is supposed to do - have fun with you in doing things. Enjoy those fry!