At this time, we do not support searching for shirts via its "Parent ASIN". The “Parent ASIN” is the ASIN that shows your shirt with no specific color or size. It will be the ASIN that is listed in your Merch by Amazon dashboard.
You will still be able to search for your shirt by any of the "Child ASIN’s" such as the ASIN that would sell a black shirt, in size Kids 10. However, please note that the preferred method for searching for a shirt is by brand name and/or title. This is how most customers will be discovering your shirts, and it is the easiest for customers to navigate.