I want to substitute flax meal for chia powder - what would be the ratio? The recipe calls for 1/2 cup chia powder. Thank you

You may have to experiment to find out how much flax to replace the chia. Usually, chia is the better thickener so you will need a bit more flax to have the same thickening power. This is a good read from Vitamix: https://www.vitamix.com/us/en_us/adding-flax-seed-vs-chia-to-your-recipes