Is there a term for a child born after the death of its sibling?

A couple loses their only child and some time later they have another child. Is there a term for that second child? I once heard a parent use a phrase to describe it, but can't remember anymore.

I believe ‘rainbow baby’ is what you're looking for.

From Wikipedia:

A rainbow baby is a term for a child born to a family that has previously lost a child due to miscarriage, stillbirth or death during infancy

Also according to Lexico:

A baby born subsequent to a miscarriage, stillbirth, or the death of an infant from natural causes.

Edit:

As @Pam pointed out in a comment below, Google Ngram shows a spike in the usage of rainbow baby in recent years:

I have family experience of this and it was described as "second and only child."

It's often a difficult topic for the parents to discuss and the above statement is easy to understand.