Confusion on Family Sharing; do both Apple IDs need to share (bi-directionally) to play each others' content?

Years ago, my wife was (accidentally) logged in to iTunes and bought a movie using her Apple ID. We have always used my Apple ID, so this was a rare fluke. Forward to today and this movie somehow still appears in my ("husband's") Music on Mac (1.0.6.10) library with her Apple ID as purchaser. A good thing.

These days I am always logged in to my husband Apple ID on both the iMac (Catalina 10.15.7) & the Music App/iTunes Store. We've stopped using her Apple ID. Not unexpectedly, I cannot play this movie - I am logged in to the wrong Apple ID to play it.

I want to play this movie within my Apple ID Music on Mac world. Family Sharing does this.

I want to Family Share so my Apple ID/Library can play my wife's purchased movie. But to accomplish this, I am not sure if:

(1) I need to Family Share my library with her (I send her an invite) -or-

(2) should she send me a Family Share invite? -or-

(3) maybe we both need to share - bi-directional invites?

Which of these three accomplishes my goal?

[Or maybe there's a way I can transfer this movie to my Apple ID? Which, I think, is impossible?]

Thanks!