To start with the hoglets will probably follow mother hog around. Hopefully she will keep bringing them to the supplementary food as well as doing a bit of foraging with them. They grow very quickly when they are young, and the weather is still quite mild, so they may have time to put on enough weight to survive hibernation. I would offer them as much food as they eat. i.e. if it is all finished offer them a bit more until you work out the right amount.
So I would keep offering them food and then in a few weeks times, weigh them. The minimum weight for hibernation is 450g, but if the weather is still quite good and they are turning up regularly for food they might be ok for a bit longer weighing a bit less than that. But you can review the situation at that time.
If they are still very small and light in weight you may be able to find a hog carer/rehabilitator that can take them in until they are large enough to be released. You can find details of your nearest carers/rehabilitators by ringing 01584 890801. They will know the local weather conditions and will be able to give you more specific advice.
Normally each hog would need a separate place to make a hibernation nest, so if you are able to fit in any more hog houses, that might be useful for them. They use a huge amount of material in a good hibernation nest, so as much nesting materials left around as possible would be good.
Don’t forget that water is best left available all day every day, including during the winter.
Good luck. I hope all goes well for them.