Do parents on non-O visas need separate bank accounts for residency applications in Thailand?

Two parents on non-O (guardian) visas inquired about the bank account requirements for obtaining residency. They asked if they need to have separate accounts with 500,000 baht each or if a joint account with that amount would suffice. Comments clarified that each parent must have their individual account with 500,000 baht due to immigration rules, as using a joint account might not be accepted by some offices.