AITA for refusing to use the money I saved for my stepdaughter 18th birthday gift to help with my daughter's treatment?

NTA. Though a few things OP said may have been a little insensitive, I do not think OP was wrong to deny this request. This couple is right in the verge of AH territory. They come off as entitled, but looking further into it their desperation signals to me that they may need some type of counseling. It is not the same, but I myself have suffered a loss as one of my daughters passed away shortly after her premature birth at 21 weeks. I understand their grief and their desire to try again, but what they need to realize is that a baby will not fix what they have been through, nor will a baby make up for all the previous losses. Bringing a child into this relationship out of pure desperation will end in disaster so they need to take the time to heal. The FEW months that it will take them to come up with the money may well be a blessing.

/r/AmItheAsshole Thread