DH's sister upset about him wanting to be a known donor

[lifeisarollercoasterbaby]

About 3 months ago some good friends of ours approached us to ask if DH would be a known donor for them, using IVF. We were very surprised by the request, but had several catch ups with them to understand how it would work and the implications, and after much debate decided it was the right thing to do - we both initially had concerns but they were answered and now we're both happy with the process and to go forward.
DH will not be 'dad', but will be a family friend that the child can ask questions of as they grow up, on the research they have done this is good for the child (has been confirmed to us by a child psychologist).
Recently they contacted us, saying that they'd got some advice and that we should inform DH's immediate family - essentially his mum and sister. Our friends said they were happy for his family to have contact with the potential child, but they wouldn't be considered 'grandma' or 'aunty' etc (same as the fact that DH isn't Dad).
So we told them, face to face, explaining why we'd come to the decision.
Enter - disaster!
DH's mum is calm but worried about the impact the potential future child will have on our family... fine, I can understand that - there is risk involved.
DH's sister is angry, hurt and very upset - mainly saying DH is abandoning the child and denying her the right to be an aunty to the child. She's accusing DH of being cold and unloving. She's saying she will love the potential child as much as she loves our own two children and will not accept that she can't see him/her on birthdays, christmas etc.
We've tried talking to her several times but she's now saying she can't sleep, it's affecting her work & life, we've upset her too greatly, we've caused a rift in the family, etc etc.
This has obviously upset DH (and me!) a lot as during her upset periods about this she has said some pretty nasty things about both of us and although she can be a handful, she's his sister and he doesn't want to cause her pain.
Now we had to have IVF and had to consider donor sperm for our treatment, which is maybe why we think about this differently to her. To us, family isn't necessarily genetic - it's so many factors that genes are only a small part of.
So now we're in a dilemma - do we put his sisters feelings first and say no to our friends (even though it feels like emotional blackmail) or do we go ahead and let her hopefully get over it in her own time...
Thoughts?

I think it’s completely irresponsible and selfish to carry on with this, it sounds like a ridiculous set up. The amount of jealousy, insecurity and problems this kind of thing will stir up with relatives, your kids and the kid conceived is exponential in later years. If your DH is so shy and retiring this sperm donation probably gives him a boost to his ego. It’s not altruism to donate sperm as a married man when there are so many anonymous sperm donors available, not to mention enough kids in the world already. And with the situation with your sister I just wouldn’t go there. It sounds like a mess.

People do have the right to know if they have a living blood relation, which is one of the many reasons why UK donor children are now able to search for their bio parents.

This is a right that only goes one way - the children have the right to search for the donors, but the donors can't search for the children. And absolutely no one has a legal 'right' to see a nephew or niece.

life you've obviously thought this through extensively. I think you've done everything right.

however all our research has been that if us and the parents are open right from the start and talk about it & explain it honestly then it minimises this risk. The child grows up with this as the ‘norm’ rather than a surprise later on

I'd agree with this 100%. Kids who find out they are adopted later tend to have a much much harder time adjusting than kids who know from the earliest years, who ask their parents lots of questions then they accept it.

If this thread is getting to you, walk away from it for a while. I still don't think your SiL has any right at all to throw these tantrums and tbh since you said she was generally a prima donna, I'd be tempted to be very careful what you share with her in future.

I think the "respect our decision" should come from your husband, her brother, though, if at all possible.

This is a right that only goes one way - the children have the right to search for the donors, but the donors can't search for the children. And absolutely no one has a legal 'right' to see a nephew or niece

With donors yes, but biological parents have the right to try to trace adopted offspring, and can make contact if that child is also looking for them.

I said nothing about 'legal' rights to see the child anyway, GP and SIL have none which is presumably partly what disturbs them.

I would be especially cautious about this kind of arrangement if I were the other couple (i.e. the ones becoming parents) because whilst it's true that they'll be the only legal parents of the child, there have been lots of really difficult cases where the relationship with the known donor has become difficult and he's ended up applying through the courts for involvement in the child's life. The donors often succeed in these cases, especially if there's been some kind of relationship with the child before. I'm sure your DH doesn't intend to do that but these cases often seem to start out with the best of intentions before the child is born but then relationships and emotions become messy and it can end up in a really acrimonious dispute.

E.g. here's a recent case where both the donor AND his parents got contact with the child www.bailii.org/ew/cases/EWCA/Civ/2018/305.html