Perfect stain remover concoction for baby clothes

How to remove old stains and current stains on clothing? We are reusing all of my daughters old clothes for current baby in December since it’ll save us a lot of money but she had a lot of spit up moments due to her reflux . I was wondering if there was a perfect concoction that has worked for anyone to get those yellow spit up stains out or food stains that seem to be everywhere after eating that detergent and name brand stain removers seem to not remove. Any advice is welcome.

We also have a lot of hand me ups that we’ve received over the year that she couldn’t fit into because she already out grew that size that have minimal stains that I’d like to get out before tossing the clothing out.