If Elon is still in consideration, a current parent confirmed the merit scholarships can be stacked.
There are also posts in that thread about stats and merit received that may be of interest to @momsearcheng.
For example, “My daughter applied EA this year with a 3.95 unweighted, 4.98 weighted and a 1420 SAT. She was admitted with Presidential Scholarship and then applied for and was accepted into Honors Fellows program. I’m not sure if that helps you but it gives you an idea for what is needed for additional scholarships.”