We did a similar thing. Early on, our toddler proposed the name Bin-ban for his upcoming sister, and it stuck.
We have a lovely video of the toddler explaining to Grannie a few hours after the birth 'her name is Bin-ban'. 'Oh <long pause>, yes, but she has a real name'.
We called her Bin-ban for a few more weeks until she sort of grew into her 'real' name. That beautiful little original name is a very fond memory for us.
Our son proposed “Caterpillar Pop” for his looming sister which I always liked. “Mustard” was the codename for another unborn child (my sister’s, I think).
We have a lovely video of the toddler explaining to Grannie a few hours after the birth 'her name is Bin-ban'. 'Oh <long pause>, yes, but she has a real name'.
We called her Bin-ban for a few more weeks until she sort of grew into her 'real' name. That beautiful little original name is a very fond memory for us.