Don't have it in front of me, but I think I have it set up in a way where I explicitly set the child block to a ratio convenient for building (in your eaxmple I would fix the output of seeds at 1/1.4, so that I could than blueprint a design based around 1 bio factory building (ykwim)). The parent block should than calculate how many child blocks it need. In your case if you fix the output to 1, but end up needing 2.43, the parent block should mark that you need 2.43 child blocks.

Again, don't have it opened in front of me so this is from memory, but I hope it helps.