For John 15:11, we find (from BSB), "I have told you these things so that My joy may be in you and your joy may be complete."
By the definition created in the question, the meaning of "in" here is #1. This is rather easy to pick here is the reason given by Jesus for "injecting" His joy into the disciples was to make their joy complete.
I believe this meaning is also clear from the grammar of the phrase, ἵνα ἡ χαρὰ ἡ ἐμὴ ἐν ὑμῖν ᾖ = (literally) "so that the joy of me in you may be".
These things have I spoken unto you, that my joy might remain in
you.—The better reading is, . . that My joy may be in you. The joy
thought of is that which Christ Himself possessed in the consciousness
of His love towards the Father, and of the Father’s love towards Him.
The brightness of that joy lit up the darkest hours of His own human
life, and He wills that it should light up theirs. In the
consciousness of their love to God, and of God’s love to them, there
would be in them, as part of their true life, joy which no sorrow
could ever overcome.
Similarly, Maclaren observes:
Our Lord’s wonderful words suggest that they who accept His sayings,
that they who have His word abiding in them, have in a very deep sense
His joy implanted in their hearts, to brighten and elevate their joys
as the sunshine flashes into silver the ripples of the lake. What then
were the sources of the calm joys of ‘the Man of Sorrows’? Surely His
was the perfect instance of ‘rejoicing in the Lord always’-an unbroken
communion with the Father.