I ASSUME that H&W can jointly set up a grantor trust, but I am not sure. Since most GTs are ignored and no EIN is acquired and no 1041 is filed, any income goes on the 1040 anyway.

If H&W can do it, why not more than two, perhaps unmarried to each other, like 3 siblings? The problem is an investment account will only report one SSN, and then that person has to report 100% and Nominee out the others' shares. 

What a mess.