I think you already know the answers.
Form 3520 is required if the total gifts are more than $100,000, it does not matter that the gift was split into 3 smaller parts. (And don't play games here. If this is a legitimate gift from that family to your spouse, just report it as it happened. Playing word games is what gets you into trouble.)
The form is filled out with the name of the gift recipient, but the spouse's taxpayer number is also required.
Since this is a gift from foreign person(s), your spouse only needs to fill out the identification section and part V.
Form 3520 is not included with your tax return, it is mailed separately to the address in the instructions. The deadline is the same (April 15, 2022 for gifts made in 2021).
