People think there's something cute about kittens being born in their homes, not thinking about anything but their own selfish romantic notions, especially not the health of the poor mum cat or the lives of those 4 or 8 rescue kittens that could have gone to the homes she's aiming her kittens at.
If she wants kittens to keep, why not take her to a rescue to meet some pre-made that she can choose the colour, sex and temperament (none of which you can do with home-made kittens) and take home in a box with her, without all that risk to her own cat.
If she doesn't want kittens to keep, then ask her to examine her own motives for putting her cat through all this risk, and bringing resultant kittens into a world where they are unlikely to find homes. Is she broody? Or perhaps thinking of selling them as commodities?
If she's thinking of selling them, and you want to get really brutal, you might also show her the *Bumtree (sic) site, so she can see how many thousands of cats and kittens are being offered for sale or free of charge by stupid people like her who assume, wrongly, they could make money from prostituting out their poor cat.
On the other hand, if she seriously wants to be a mid-wife to a Mum cat, see if the local rescue has a ready-to-pop Mum who needs a Foster home for herself and her babies. If your friend has the time and inclination to indulge her own cat a litter or two, maybe it's a resource just waiting to be tapped and she might help a genuinely needy Mum cat get the care she deserves, then your friend can offer these kittens to the home she had lined up for hers?
Once she's seen how it works in real life maybe her fantasy of cute ikkul kittuns will seem less romantic.
Salute what you are trying to do, I hope she's a true friend and listens to your advice.
