Resources:

https://www.irs.gov/taxtopics/tc310

https://www.bogleheads.org/wiki/Coverdell_Education_Savings_Accounts

"Special care must be taken for multiple accounts established for a beneficiary by different donors (for example, a parent and a grandparent) that the $2,000 annual limit is not exceeded, since excess contributions are subject to a 6% excise tax."

Just as examples...