grouping email threads from different conversations because of same subject line

It seems like this has been an issue for at least a decade now, but I haven't seen any answers since 2014 (unless I missed them). How has this not been fixed yet?

Problem: I have sent emails to multiple people in the last week about totally different topics related to my son, but I have used only his first name in the Subject line in the email to each person. My phone has now decided that my conversations with his teacher about school and his soccer coach about not being at his game this weekend are all the same conversation, so it has lumped them all together. How is there not a way for Mail to recognize that the sender is different and therefore the email threads should be kept separate?! Or at least an option for me to say, "Remove this email from the conversation" or "Create separate conversation?" I don't mind customizing it if I just knew how to! I do like to have the chain of emails back & forth with his teacher all in one thread (so I don't want to turn it off in Settings), I just don't want the soccer emails lumped in with the school emails since they are in no way related.

Thanks for any help that can be provided!