Social groups will auto-calculate the shared haven/sanctum/hollow Merits of all characters in that Social Group. Aside from family (seeming/clan/path/auspice) and organization (court/covenant/order/tribe) social groups, this will work for any new/private group as long as all members character sheets use the correct notation.
TL;DR: The Merit detail must match the Social Group name.
For those wondering about some of the Merits that require more detail, that can be put in the Notes area of the character sheet.
For example, a Library would be recorded in two places:
Library (yourcrewname) = 2 <---- sanctuary Merit section
Library (Hedge Fruit, Oneiromancy) <---- Notes section