Child ASIN divorced from Parent

So I have a parent ASIN with child ASINS that are the colour variations which I’ve sold a few of.

For some unknown reason the child has been split from the parent and is no longer under the parent ASIN.

Is there any way I can add this child ASIN back to the parent and keep the same ASIN number as it is a FBA item and I do not want to have to ship it back to myself and re-label it.

TIA