How to introduce a related person's name plus a possessive? [closed]

In English, the possessive (or genitive) case denotes "ownership, measurement, or source," and is marked by 's. (ThoughtCo, "Possessive or Genitive Case").

Once you mark something in the possessive case, it is possible to nest the noun phrases even further:

the boss's dog (the dog owned by my boss)

the coworker's boss's dog (the dog owned by the boss of my coworker)

my friend's coworker's boss's dog (the dog owned by the boss of a coworker known by my friend)

It is also possible to put phrases or even clauses in the possessive case. Laurel J. Brinton explains this behavior in The Structure of Modern English: A Linguistic Introduction, p. 96:

[After the sixteenth century] it became possible to add the possessive ending to an entire phrase, a construction called the "group genitive". What precedes the possessive ending need not be a single-word compound but can be a phrase, as in my neighbor next door's dog, or even a clause, as in a woman I know's niece.

So to make a group genitive, you only need to put the possessive at the end of the phrase or clause. In your case, the phrases you're dealing with put together a noun phrase (my father) and an appositive that identifies them (Bob Harry). Here are the pairs in your post:

my father Bob Harry

my sister Juliet

Juliet's husband Eric

To make any of these phrases possessive, you only need to add to the end of the phrase:

my father Bob Harry's car

This is what you did in example 1. Grammatically the example is fine. Contextually the example is odd - rare is the situation where I refer to my father, give his name, and state that I borrowed his car in one sentence.

Example 2 errs in separating the noun phrase and the appositive, which leads to reading them as two separate entities. ("Bob Harry's car" reads like it explains what "my father" is.) Example 3 reduplicates the genitive case in an agrammatical way - you don't need to make both a noun and its appositive possessive.

For the next three examples, example 4 is correct since "my sister Juliet" only has the possessive at the end. Example 5 is grammatically fine since you are allowed to nest possessives, if unnecessary in its avoidance of the more concise term "brother-in-law." Example 6 is also fine under the same conditions.

Finally, example 7 reads fine when rendered without the comma:

I borrowed from my father Bob Harry my sister Juliet's husband Eric's best screwdriver.

If you're worried about getting confused with all the noun phrases between "my father Bob Henry" and "my sister Juliet's husband Eric's best screwdriver," you can move the prepositional phrase to the end:

I borrowed my sister Juliet's husband Eric's best screwdriver from my father Bob Harry.