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Hi.

I'm just curious to know if there is any difference between

[1] I'll join you,

[2] I'll join on you,

and

[3] I'll join up on you

?

Any and all your help would be very much appreciated.

Hiro
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2 and 3 are kind of strange to me, but I've found several instance of 3) on the Web.

However, the established usage is:
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Phrasal Verb: join up

To enlist as a member of an armed service.

Phrasal Verb: join up with someone

To come together with them for joint action, etc.

http://www.allwords.com/word-join%20up.html
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Comments  
i know that, to use "join", you should say A join B
but for "join up", you should say A and B join up.
however, i haven't ever seen "join on" ..
 Marius Hancu's reply was promoted to an answer.