First, welcome to BYH!
How much do these kids weigh? Are they from large litters?
I do think you need to increase each feeding. The kid might have over ate on the 6oz feeding.
It is normal if they take a lot of milk on the first feeding, they might not want as much on the second feeding. But, the appetite should come back by the third or fourth feeding.
Are these guys in your house? Have you taken their temp?
I would look at giving a B complex injection, this will help stimulate appetite. If you can get JumpStart Plus gel from TSC that might be good too. This year we had a mini kid that was just stubborn. She didn't want to take the bottle, I finally got her on the big, clear nipples from TSC. She didn't have the vigor that her 2 siblings have/had. We gave some B vit (thiamine actually) and she seemed a bit better. I have her on 5oz, 4x a day (not a dwarf).
I had a set of quads born 10 days ago, these are their birth weights:
1st doe (Dot) 3lb 1oz
2nd doe (Not Dot) 2lb 13oz
3rd doe (Splash) 2lb 9oz
Boy 3lb 5oz
The first few days they were on 2oz every few hours (as they told me when they were hungry LOL). A few days after that they were put on 3oz 4x daily and a late night feeding if they cried for it, sometimes I'd give the big boy some extra if I thought he needed it. Now they are 10 days old and are going to 4oz 4x daily. It's not good that they've haven't eaten in 12 hours, but not critical at this point. You just don't want it to continue.
Are they able to run around and play? Kids that are in dog crates or penned up might not want to eat because they don't use and energy. When we have kids in the house (we have 8 in some large crates due to the cold weather!) we need to let them bounce and play before they eat. This is very important for the larger breeds especially.
The breeder really should have had them fully trained to a bottle before they were sold. The breeder might not be experienced, but it is not good practice to just sell young kids who haven't been on the bottle.