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In the same way as user accounts, custody management is a service who which can be provided by organizations within the FinP2P as a networkprotocol, and the expectation is that if and when required, financial institutions or their external custodian providers can provide those service for their clients, so when a front-end app calls the FinP2P Application API, the required transactions needs will be routed to be signed by the appropriate entity.
It is important to note, that in the world of Private securities today (unlike with Public securities), the vast majority of security holders hold the securities directly in their own name (as defined in cap tables and investment or debt documents), and therefore the network protocol supports that option as a defaultwell.