[FE7] FE8 Triangle Attack

Is it possible to implement the triangle attack like in FE8?

I mean, 3 units can perform it when all are Pegasus Knight, but if one promotes to a different class than Falcoknight, just that unit can initiate the attack.
Is that doable for FE7?

I think there’s an attribute for it in character abilities but i vaguely remember it being a pain in the ass to customize it beyond “if there’s a triangle, make a crit”. this unfortunately includes the peg knight animations