As others have stated, you can only apply ED1 (or just ED) to one single school.
If you apply ED to two schools, you should assume that they will notice, and you should assume that you will automatically be rejected by both schools.
I am not a big fan of applying ED at all. You should only apply ED if both of the following are true: (1) It is clearly the student’s top choice; (2) Either you are fine being full pay, or the Net Price Calculator shows the school as being likely to be affordable. If you do not have one single school for which both of these are true, then do not apply ED at all.
If one of the schools in your post is clearly your son’s top choice, and if it appears likely to be affordable, then your strategy is clear. Apply there ED. Apply to other schools either EA or RD.
I am however a big fan of either EA or rolling admissions (one or the other depending upon which school you are applying to). Getting your application in early makes the point that you are interested and lets them look at it before they are totally swamped. Getting an acceptance back early can reduce the stress of the entire process (and university admissions can be a very stressful process, particularly for the student).
Also, there are a lot of very good universities in the US, and just as many outside the US. If your son is remotely competitive for any of the schools listed in the original post above, then he will get accepted to very good universities. While these may be slightly lower ranked than the top schools, they will provide a great education and great opportunities for students.
We have some experience with highly ranked schools, and this does include both: (1) graduating from a highly ranked university and then spending a career working alongside people who graduated from a long list of other schools, with no one (including us) caring where anyone got their degrees; and (2) getting a bachelor’s degree at a university ranked somewhere vaguely between 50 and 150, and then getting a graduate degree from a university that is similar in selectivity to schools that were listed in the original post above. At this point the one perk that I see from having attended a famous school for undergrad is that I still get to sail there from time to time. This is not the reason that I typically hear regarding why anyone would want to attend a famous school.
Also, make sure that you son applies to safeties, look for a good fit, and keep your budget in mind (which includes figuring out what your budget is). If you son is considering a major where graduate school is likely, then budget for it also. PhD’s are usually fully funded, but master’s degrees, law degrees, MD’s, DO’s, and DVM’s typically are not.
“A good fit” and “affordable” are typically the most important parts of this entire process.