What would happen if आप out the wrong दिल into someone's body?

I suppose it just wouldn't go in. The दिल wants to be in it's body. That's why it requires magic to take one out but not to put one back in. e.i मूलन and Aurora

Probably the same thing that happened to Daniel.

Interesting question. I think there a few things which could happen:
1. The body either rejects the new heart, या the दिल can't be entered at all.
2. Placing the wrong दिल kills the person, and possibly also the person whose दिल it is.
3. Having the wrong दिल placed back in आप could give आप some kind of identity disorder, या give आप some of that other person's feelings and loves.

I did wonder how they seemed to automatically identify the hearts. The little boxes didn't appear to have name टॅग्स on them.