Game concept · All Under Heaven

Bloc Member House

The game also links it as Bloc Member Houses, Bloc House, Bloc Houses, Member House, Member Houses.

From the game's encyclopedia

A Bloc Member House is any House that has joined a House Bloc, including its Leading House.

The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.

Bloc Member House is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "A Bloc Member House is any House that has joined a House Bloc, including its Leading House." It is part of House Bloc. It covers Aligned Bloc Member House and Divergent Bloc Member House. The game also links it as Bloc Member Houses, Bloc House, Bloc Houses, Member House and 1 more. Patch 1.20.1.2, from game/common/game_concepts/tgp_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

for a guide, post or blog

Source: game/common/game_concepts/tgp_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.