Crab apples are OK for pollinating so they can fill a gap in your orchard and you should get more fruit on the other trees as a result.
I guess the trees are still small. It is worth taking out any damaged fruit or the small ones where you have a bunch of 2 or 3. The others will grow bigger then.
Here, it has been a dry summer and my little trees are struggling to stay alive as they establish their roots. I got a couple of tiny apricots and a few apples are growing but I shouldn't expect much this year with new trees.