Although I'm no Greek scholar (but I play one on TV), but:
This much is true:
"Mt 24:45-47 and Lu 12, uses the definite article 'ho' with reference to F&DS."
I don't see how the definite article requires this conclusion:
"Therefore is composite and does not apply to individual anointed ones nor to GC."
Rather than the article before "slave," what really directs the meaning is the opening phrase, tis ara estin (Who really is, who then is). Both parables (Lu 12 and Mt 24) begin with this.
Concerning ara (#686), AMG's Greek-English Dictionary says, "As an inferential particle ara means 'therefore,' 'then,' 'now,' 'consequently,' marking a transition to what naturally follows from the words preceding."
Leading up to the parable in Luke 12, Jesus tells his disciples (using plural pronouns) to seek first the kingdom (vv.32-34), and to be hard working slaves who are constantly watching for their master's return (vv.35-40). Peter then asks if Jesus is saying this to them or to all (v.41). Jesus' response is the parable of the F&DS. (Which, if you are familiar with the gospel accounts, it is not uncommon for Jesus to answer a question with a question. Many examples could be cited here.)
The setting in Matthew 24 is just a few weeks later in time. Verses 43, 44 are almost identical with Luke 12:35-40. Again using plural 2nd person pronouns. Then Jesus gives the gist of the parable that he gave in Luke 12.
The material in Luke 12:35-40 and Matthew 24:43, 44 is directed to a plural group. Especially in Luke, though, with Peter's question of who it applies to, the parable of the F&DS uses a singular example, and naturally would help each listener to determine if it applied to him. In a sense, it takes a plural or group discussion and focuses it on the individual.
Also giving meaning to whom the parable applies is the principle Jesus cites at the end of the parable in Luke. Verse 48 says, "Indeed, everyone to whom much was given, much will be demanded of him; and the one whom people put in charge of much, they will demand more than the usual of him."
Based on this principle, the application of the parable would seem to be for "everyone to whom much was given," and 'the one whom [the master] puts in charge of much.'
How would any of this context make any sense at all, if Jesus is describing a handful of men some 1900 years in the future?
I will say this also. Whenever the Society quotes the parable, they rarely, if ever, include the context. That practice is most useful if you want to make some implausible application. Context's have a habit of getting in the way.
Hope this helps
Take Care