mpo_blood_brother_remove_family_opinion_effect

mpo_blood_brother_remove_family_opinion_effect = {
	hidden_effect = {
		#Add blood brother close family opinion to actor's family
		save_scope_as = former_kin
		scope:other_blood_brother = {
			add_to_list = other_blood_brother_family
			add_character_flag = unhandled_family
			every_child = {
				add_to_list = other_blood_brother_family
				add_character_flag = unhandled_family
			}
			primary_spouse ?= {
				add_to_list = other_blood_brother_family
				add_character_flag = unhandled_family
			}
		}
		#Remove other family on former kin
		while = {
			limit = {
				any_in_list = {
					list = other_blood_brother_family
					has_character_flag = unhandled_family
				}
			}
			random_in_list = {
				list = other_blood_brother_family
				limit = {
					has_character_flag = unhandled_family
				}
				save_scope_as = other_blood_brother_picked_family
				remove_character_flag = unhandled_family
			}
			scope:other_blood_brother_picked_family = {
				remove_opinion = {
					target = scope:former_kin
					modifier = blood_brother_close_family_opinion
				}
				scope:former_kin = {
					remove_opinion = {
						target = scope:other_blood_brother_picked_family
						modifier = blood_brother_close_family_opinion
					}
				}
			}
			clear_saved_scope = other_blood_brother_picked_family
		}
	}
}

As written in game/common/scripted_effects/09_dlc_mpo_scripted_effects.txt.