Hide child products in parent product page under grouped product in WooCommerce

I’m trying to hide the child items from the parent product page. Like this -> https://nimb.ws/g4ny0W

Reason is I’m doing a modification to allow something like “Buy 1 Free 1” in grouped products, meaning if you buy parent item, you get child item too! No need to click on child item and add it to cart. It’s “forced” into your cart.

I know I can use WooCommerce Chained Products but another plugin I’m using is not compatible with it.