Definite form of "you"

[Woods]

How far is that sentence correct/idiomatic:

It will turn things in your (I mean both of yours) advantage.

[linguoboy]

How far is that sentence correct/idiomatic:

It will turn things into your (I mean both of yours) advantage.

It's fine, though if I were writing that sentence I'd prefer to be more concise and say "...to both of yours advantage."

[Woods]

Thanks :)

[Woods]

Can I sneak in one more:

You never understand what the point in it is (that's how I would say it)

You never understand what's the point in it (some people would write it this way, and I just caught myself typing it - how correct would that be?)

[JackFrost]

Can I sneak in one more:

You never understand what the point in it is (that's how I would say it)

You never understand what's the point in it (some people would write it this way, and I just caught myself typing it - how correct would that be?)

Personally: you never understand what is the point in/of it. Putting "is" at the end sounds clunky.

[Dormouse559]

For me, the "is" at the end sounds better, and I prefer "of".

You never understand what the point of it is.

[JackFrost]

I also prefer "of", but after looking it up, "in" is apparently an alternative way of saying it. Just not a way I would say it.

[Woods]

From https://en.oxforddictionaries.com/definition/point:

4.3in singular, usually with negative or in questions: Advantage or purpose that can be gained from doing something.
‘there was no point in denying the truth’
‘what's the point of having things I don't need?’
‘There's no point in splashing out on expensive designer gear if your skin is as rough as sandpaper.’
‘There is no need to stock up on supplies - and no point buying a gas mask.’
‘The Board say that there is no point testing or treating anyone who has eaten these products if they are well.’
‘It's not that I even really understand the point of using conditioner anyway.’
‘Is there any point inviting comments when planning objections are submitted?’
‘There's no point in being an artist if your goal is to produce the same thing for your entire career.’
‘There is no point in moaning about it.’
‘There is no point in denying the language in Shakespeare is problematic.’

and so on...

It seems they're using three different variants - in, of and the present participle without a preposition - interchangeably.

It's too bad we don't have some Britons here to have their say too. I don't know why, but I woudn't think of saying "the point of" myself, even though I'm mostly exposed to American and non-native English. Well actually I would, but only if the complement is a noun, not a verb. (Did I use the right grammatical term here - complement - I don't know )

[Dormouse559]

It seems they're using three different variants - in, of and the present participle without a preposition - interchangeably.

Not interchangeably. Notice how "in" and the bare present participle only appear after "no/any point". The only instances of "of" are after "the point". Though I'd never noticed that pattern before, it pretty much matches my usage. By contrast, "There's no point of doing sth" sounds wrong to me, as does "What's the point (in) doing sth?"

[Woods]

sent participle only appear after "no/any point". The only instances of "of" are after "the point". Though I'd never noticed that pattern before, it pretty much matches my usage. By contrast, "There's no point of doing sth" sounds wrong to me, as does "What's the point (in) doing sth?"

Good observation!

There are more examples in the Oxforddictionaries page, I'll try to check them when I have time (not that much lately)