Edison format ruling
Symbol of Heritage

Card effect (current official text)Activate only while there are 3 Monster Cards with the same name in your Graveyard. Select 1 of those monsters, Special Summon it, and equip it with this card. When this card is destroyed, destroy the equipped monster.
Rulings
- "Symbol of Heritage" targets 1 monster in the GY. If your opponent chains "Disappear" to remove from play the targeted monster, the effect of "Symbol of Heritage" does not resolve. But if they chain "Disappear" to remove a different monster with the same name, then the targeted monster is still Special Summoned even though there are now only 2 of it in the GY.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.