In order to both legitimize and justify the "house type" merits (Haven, sanctum, safehouse, etc.) in a game of this scope, we are simplifying and house ruling (hah) the merits into a single system. The following aspects are now universal to all "house types", meaning that in reality you can have a shared house between multiple supernaturals: Size, Security, Library, Archive, Workshop, Armory, Cache, Workshop and Traps.
Errata to the Above:
--Size is now free. Dots in size are determined by your available resource dots, to a maximum of 5 as described in most of the Core books. Remember that police with large houses look suspicious. The resources can be provided by retainer, but remember loyalty issues. The Luxury merit can provide any Size dots you wish.
--Security represents all it does in a standard book description (bonus to initiative, penalty to breaking in, etc) but can also be used to help justify security measures found in Armory.
--The Library merit for Mage and Second Sight is now replaced by the Library merit from Vampire. It provides a bonus to research rolls with Academics and Occult. Second Sight'ers are still limited to a purchase of three dots.
--The Archive merit for Lost now replaces the Library merit for Mage and Second Sight. Each dot represents a specialized field of interest that reduces research time. The bonus for the Library merit to research is still viable. Second Sight'ers are still limited to three dots.
--The Armory merit represents weapons, as outlined in Banishers (Each dot is 5 size points of equipment).
--The Cache merit represents non-weapon equipment.
--The Traps merit works as per the merit in Hunter, but is applicable to all Houses.
--The Workshop merit allows for a different "craft" per dot with a small bonus to that craft.
Supernatural Specific Aspects:
--The Hollow for Lost remains unchanged, as it is a magical house-type. Size is not free, as it is a magical location. This does not prevent Lost from participating in a "mundane House" outside the Hedge alone, with other Lost, or with multi-genre allies. It simply means that a Hollow is a separate and unique advantage to the Lost. The Archive, Workshop, and Library merits can be added to a Hollow.
--The Haunt for Geist gains the above qualities, but with the following additions for Geists only.
---Fluidity: access bonus to the Underworld
---Residue: represents 1 plasm per day, not week, per dot
---Utility is removed from play.
--Havens for Vampire retain Location. This can be added to a multi-genre house, but only Vampires and Ghouls may purchase it.
--Havens for Vampire retain the Tomb aspect, but only a single vampire may purchase it. There could be a tomb in a multi-genre house, but that isn't necessarily smart or safe.
--Havens for Vampire retain the Occultation aspect, but should only be purchased by Mekhet if possible.
--Chapter Library for Vampire can only be purchased by Ordo characters but is considered a separate merit from Library and Archive and stacks with those merits.
--Geomantic Nexus for Vampire is a merit that can only be purchased by Ordo characters but can be applied to a multi-genre house, benefiting any within. The Geomantic Nexus Size merit is combined with "House Size", while Geomantic Nexus Potency remains valid.
--The Hallow merit remains unchanged, and can be applied to a lone Sanctum or a multi-genre house.
--The Locus merit from Territories is now valid, and can be applied to a lone "werewolf house" or a multi-genre house.
[Note: It is possible to have multiple "fuel" merits all applied to the same house. This is a potent but not necessarily unusual aspect of the World of Darkness metaphysical geography.]
--Safehouse: Secrecy is removed from play.
--The Torture Suite merit from Hunter can now be applied to any "House." As a 1 to 3 dot merit, it can be shared and used by anyone with dots in the House, per standard rules. It can still remain separate from a house (such as a warehouse room, etc.)
--The Guardian merits from Mage can be applied to any house, as long as there is an ability to summon, bind, or control said entities. The Guardian Retainer merit is not a Sleepwalker if purchased by a non-mage (though if a mage is 'sharing dots', it can be). These merits can be shared by multi-genre inhabitants, as long as there is a shared ability to control them (ask Woderator if confusion on how this is possible).
[The Cruac ritual Roving Hut can be used on a multi-genre house, but can only effect Size, Security, Library, Location, and Occultation.]
As per usual, the Carthian and Crassus ghoul ability to purchase Havens at half cost remains in play.
Errata to the Above:
--Size is now free. Dots in size are determined by your available resource dots, to a maximum of 5 as described in most of the Core books. Remember that police with large houses look suspicious. The resources can be provided by retainer, but remember loyalty issues. The Luxury merit can provide any Size dots you wish.
--Security represents all it does in a standard book description (bonus to initiative, penalty to breaking in, etc) but can also be used to help justify security measures found in Armory.
--The Library merit for Mage and Second Sight is now replaced by the Library merit from Vampire. It provides a bonus to research rolls with Academics and Occult. Second Sight'ers are still limited to a purchase of three dots.
--The Archive merit for Lost now replaces the Library merit for Mage and Second Sight. Each dot represents a specialized field of interest that reduces research time. The bonus for the Library merit to research is still viable. Second Sight'ers are still limited to three dots.
--The Armory merit represents weapons, as outlined in Banishers (Each dot is 5 size points of equipment).
--The Cache merit represents non-weapon equipment.
--The Traps merit works as per the merit in Hunter, but is applicable to all Houses.
--The Workshop merit allows for a different "craft" per dot with a small bonus to that craft.
Supernatural Specific Aspects:
--The Hollow for Lost remains unchanged, as it is a magical house-type. Size is not free, as it is a magical location. This does not prevent Lost from participating in a "mundane House" outside the Hedge alone, with other Lost, or with multi-genre allies. It simply means that a Hollow is a separate and unique advantage to the Lost. The Archive, Workshop, and Library merits can be added to a Hollow.
--The Haunt for Geist gains the above qualities, but with the following additions for Geists only.
---Fluidity: access bonus to the Underworld
---Residue: represents 1 plasm per day, not week, per dot
---Utility is removed from play.
--Havens for Vampire retain Location. This can be added to a multi-genre house, but only Vampires and Ghouls may purchase it.
--Havens for Vampire retain the Tomb aspect, but only a single vampire may purchase it. There could be a tomb in a multi-genre house, but that isn't necessarily smart or safe.
--Havens for Vampire retain the Occultation aspect, but should only be purchased by Mekhet if possible.
--Chapter Library for Vampire can only be purchased by Ordo characters but is considered a separate merit from Library and Archive and stacks with those merits.
--Geomantic Nexus for Vampire is a merit that can only be purchased by Ordo characters but can be applied to a multi-genre house, benefiting any within. The Geomantic Nexus Size merit is combined with "House Size", while Geomantic Nexus Potency remains valid.
--The Hallow merit remains unchanged, and can be applied to a lone Sanctum or a multi-genre house.
--The Locus merit from Territories is now valid, and can be applied to a lone "werewolf house" or a multi-genre house.
[Note: It is possible to have multiple "fuel" merits all applied to the same house. This is a potent but not necessarily unusual aspect of the World of Darkness metaphysical geography.]
--Safehouse: Secrecy is removed from play.
--The Torture Suite merit from Hunter can now be applied to any "House." As a 1 to 3 dot merit, it can be shared and used by anyone with dots in the House, per standard rules. It can still remain separate from a house (such as a warehouse room, etc.)
--The Guardian merits from Mage can be applied to any house, as long as there is an ability to summon, bind, or control said entities. The Guardian Retainer merit is not a Sleepwalker if purchased by a non-mage (though if a mage is 'sharing dots', it can be). These merits can be shared by multi-genre inhabitants, as long as there is a shared ability to control them (ask Woderator if confusion on how this is possible).
[The Cruac ritual Roving Hut can be used on a multi-genre house, but can only effect Size, Security, Library, Location, and Occultation.]
As per usual, the Carthian and Crassus ghoul ability to purchase Havens at half cost remains in play.