Halliday & Matthiessen (2014: 238, 238n):
Recipients and Clients occur in systemically different environments … Recipients occur only in ‘transitive transformative’ clauses of the ‘extending’ type; and within that category, they occur with those clauses that denote a transfer of the possession of goods. Here the Goal represents the ‘goods’ being transferred…
They are thus the material version of possessive relational clauses. Fawcett (1988) treats them as relational rather than as material. But in our interpretation, they are simply part of a general pattern of agnation between material clauses on the one hand and relational and existential ones on the other: creative material clauses are related to existential clauses and transformative material clauses to relational clauses (more specifically, elaborating transformation — intensive relation, extending transformation — possessive relation, and enhancing transformation — circumstantial relation).