Can you tell what my foster kittens are mixed with?

You will have to go to my profile, to see them. The orange kittens fur is very very soft and silky feeling. The other kittens fur as you can see is short thick and med to coarse texture. Both kittens have long tails like the mom, but she ate part of the brown/tabby tail shortly after birth. Also I find the shape of their heads different so maybe that will help. I think the orange ones ears sit a bit more on the side as appose to on top. Any ideas would be greatly appreciated. Thanks!

It is always very hard to tell a cat's mixture when they're kittens; even adults!

I am guessing Mainecoon/domestic short hair.

They look like Domestic Shorthair kitties to me. Don't see any overt other signs. Part of the beauty of the domestic long and shorthairs are their wonderful diversity in size, shape, and temperament. You will often see glimpses of other breeds in them because they are from common ancestors. 
 

Certain areas even have their own local phenotypes. Which are special in and of themselves. You can see the amazing history of an area in their kitties. I lived in an area that had a large population of what I thought of as Ruffed Cats. They are huge, have dense fur, big feet (many with six toes), a gorgeous jade green or sapphire blue eyes, and big plumed tails. They are absolutely stunning often with dramatic points. They never seem to go feral. They are always "mostly domestic" and seem to seek out people. On the other end are the little Wild Cats. Small, compact, round heads, large eyes, point ears with big tufts, short dense rough hair usually in tawny colours, always with strong classic tabby or rosette patterns, with long black glittery guard hairs. They have striking patterns, gorgeous gold eyes, and heavy jaws (I've seen small kittens crack pheasant leg bones), their back legs are noticeably longer than their front. They bond strongly with their families if you get them as kittens, make good guard cats, but have zero interest in people in general and tend to go (or more to the point stay) quite wild. 

In my area hairless, big eared, no undercoat, short legs, very long tails, bobbed tails, and round eyes are all very rare. 

Domestic cats are special in and of themselves, and getting to know your local cat populations will help you determine if you have the natural kids of a pedigreed gentleman, or a bunch of naturally good looking domestics.

Thank you for your input.!

Mainecoon? which one, the mom? Thanks!