It is very wrong to breed a 6 month old pup on her first heat. First off she is still a baby herself and is not fully developed yet. Her bones are still soft and forming. Having a baby will only pull her needed calcium from her system to support her unborn babies.

That alone should be a big enough factor to want her to prevent her pup from being bred, but if it's not consider this....

She is breeding a mix with a border collie. Has she figured out the costs associated with having a litter of pups? What is one or more has problems? Can she nurse them to health? Does she have the time or commitment to realize she is bringing these pups into the world and she is responsible for there welfare?

Can she place all the pups in good homes before they are born or is she just hoping to make a few dollars from selling them. If the latter is her intention, she is in for a rude awakening. Breeding a healthy litter is more of a break even thing if you do it right.

Discourage your friend in any way you can. Call the shelter and let them know what she is planning and ask them for advice.