Assalamu Alaikum:

It wasn't a question of making sense, but rather what was the reasoning behind the prohibition.

At the time of the Prophet(PBUH), such science did not exist, so he did not forbid us from using surrogacy. So, when a Sheikh says something of this nature is forbidden in Islam, I like to know why. Especially since other methods of fertilization are allowed. 

Most importantly, all life is from Allah(SWT), so if a surrogate mother is used and the baby is born, this is from Allah(SWT). So I wished to see the actual daleel in this matter.  

The Sheikh stated: unnecessarily revealing your aura, which would be the case in surrogacy as well as fertilization treatment

Questionable paternity: which could  or could not be the case in surrogacy as well as fertilization treatments, since accidents happen and fertilizing the egg outside of the womb can always lead to an accident

Renting the womb: he gave this as a reason, and that it was a reprehensible act, but he gave no Islamic proof of such.

Without some sort of daleel, this would have been an opinion only. That is why the Ayat in the Quran was very important as it showed Islamically why this was not acceptable.

Salaams.

Alahmdulila

Assalamu Alaikum:

You are very blessed to have such a Sister.  I don't know if it is allowed or not... nor do I claim to know.  I do know however that it is a blessing to adopt a child.  Yes, one must be careful about lineage, if one knows it... but other than that, it is considered a blessing.  I just want to let you know as somebody who was adopted (and whose brother was adopted as well)... there is no difference.  Giving birth does not make one a parent, it's everything that comes after.  Yeah, giving birth to my sons was fabulous... but it did not make me their mother.  It was taking care of them, laughing with them, teaching them, etc. that did that.  Pray about it.  Don't worry about not loving the child the same, or what not... once you hold him or her in your arms, that will be it. 

One can adopt from the States as well as abroad.  Kazakhstan is popular, China for girls, etc.  Do research on the countries to find out health issues.

Peace.

For the first and third, invitro fertilization has nothing to do with sex.  In fact, the sperm donor and the egg donor don't even have to see each other face to face.  There is no passion involved as well.  There is no lust.  *****edited*****

I did find an article that says IVF is OK as long as the eggs and donor sperm come from the married couple, which doesn't seem possible in this arrangement.  I'm wondering if the husband could take his wife's sister as a 2nd wife until the child is born? Not sure if that would be allowed or not from an Islamic standpoint.  Just wondering.