So, if a couple is adopting a baby via arrangement with a pregnant young lady who can’t raise the child, going to the shower implies my approval of fornication, adultery, rape, or even incest?  Then I guess I committed a serious sin in going to the baby shower of an unborn child being adopted by the woman’s drug addict sister.  This child is the second such baby they’ve adopted.  The birth fathers and circuмstances of conception of both children is unknown.  DNA testing reveals only that the elder child is of Northern European and German heritage.  The second is German and East Asian, possibly Vietnamese.  The boy, baby no.1, is normal. The girl, baby #2 was born with brain damage and is developmentally disabled.  Both children are baptized and being raised Catholic. 
But even if not, I don’t understand not celebrating the arrival of a baby because of how he was conceived.  My only question for the OP is their association with the couple.  Is it a relative?  A neighbor?  Colleagues from work or school?  Someone from before you became Catholic?  Would you attend if you didn’t know about the IVF?  (I agree it is in bad taste to announce such a thing, but people these days have little to no sense of decorum.  A look on any social media makes that obvious.)
If the couple themselves disturbs you too much to attend, then at least send a card and a small gift for the actual baby. 

In that case, the adopting couple did not commit sin. It was the drug addict sister that did the sin, so that is fine to attend the baby shower, but in the case that was originally brought up, it the couple that committed the sin and is having the baby shower. So, the two cases are different.

Stay home because many of these people are getting needles

You mean for the C-sickness?  I had the C-sickness naturally, recovered, am not afraid of it.If I were, I’d be at home, isolating myself, wearing a mask, etc.  

This is why "ask a priest" is often terrible advice. It should be "ask a holy and well-formed priest if you have one"

Given the state of the Church, "ask a priest" is worthless advice where it comes to theological approaches to the Crisis.  I might make sense with regard to established questions of theology, like asking a priest about the Holy Trinity or Immaculate Conception, etc.  But questions about whether SVism is right or R&R, the answer will depend on which group the priest belongs to.

Same goes with moral theology, as in general they're probably educated in many of the core principles, but where it comes to applying them to concrete situations, and prudential judgments, you'll probably get answers all over the map.

And, sadly, there are many seminary-trained priests who simply didn't absorb much of what they were taught there.  I've known priests ordained through SSPX who didn't know 10% as much as your average poster on CathInfo.  And I've known a few priests who were ordained prior to Vatican II whose knowledge did not exceed the contents of the Baltimore Catechism.

And, sadly, there are many seminary-trained priests who simply didn't absorb much of what they were taught there.  I've known priests ordained through SSPX who didn't know 10% as much as your average poster on CathInfo.  And I've known a few priests who were ordained prior to Vatican II whose knowledge did not exceed the contents of the Baltimore Catechism.

That would exceed the knowledge of many a post-Vatican II priest.

I have a cousin who had a double lung transplant.  (No, not Catholic.)  Do I rebuke her for being alive and refuse to associate with her?  You can’t undo a lung transplant.  (Well, you can, but the doctor who does it is guilty of murder and my cousin and those that approve are guilty of ѕυιcιdє or aiding in ѕυιcιdє and murder!)  What about her daughter?  Her grandkids?  Her husband?  These are not people I see on any kind of regular basis, but I’ve often wondered where to draw the line. 

Is it my duty to correct the sins of distant relatives?  What about getting a list of people who have designated themselves organ donors on their auto licenses?  I used to check people’s licenses all day when I was a cashier and they wanted to pay by check or credit card.  Should I have corrected or rebuked each one, and if that wasn’t feasible, quit my job? 

 Now what is wrong with being an organ donor? Why do you care people have it on their license? The only people I have heard rejecting organ donation POST MORTEM are jehovas witness. In what world is it wrong to donate organs you no longer need (because you are dead)?? 

Now what is wrong with being an organ donor? Why do you care people have it on their license? The only people I have heard rejecting organ donation POST MORTEM are jehovas witness. In what world is it wrong to donate organs you no longer need (because you are dead)??

The problem with organ donation is that, in many cases, the “donor is not POST MORTOM, but living and anaesthetised. 
There are some donations, such as the eyes, which can succeed after the donor dies.
Some donations, such as one kidney, can come from living donors who continue to live after the donation.
but no donation of a singular organ, such as the heart, can succeed without extracting the organ while the “donor” is alive, thus killing him.