former_consort_was_father

former_consort_was_father = {
	OR = {
		any_former_spouse = {
			even_if_dead = yes
			this = scope:father
			this = scope:real_father
			trigger_if = {
				limit = {
					is_alive = yes
				}
				NOT = { any_consort = { this = root } }
			}
		}
		any_former_concubinist = {
			even_if_dead = yes
			this = scope:father
			this = scope:real_father
			trigger_if = {
				limit = {
					is_alive = yes
				}
				NOT = { any_consort = { this = root } }
			}
		}
		any_former_concubine = {
			even_if_dead = yes
			this = scope:father
			this = scope:real_father
			trigger_if = {
				limit = {
					is_alive = yes
				}
				NOT = { any_consort = { this = root } }
			}
		}
	}
}

As written in game/common/scripted_triggers/00_birth_triggers.txt.