ISO Upgrades for Delta International Flight

I am traveling this summer with my family. I am looking for four upgrades for my Delta Airlines flight. Portland to Rome in July 2019. I am not exactly sure the type of upgrades I need, but I would like to change from our seats to Business Class. I can trade Whiskey or wine.

Delta systemwide upgrades are not transferable (unless one is traveling on the same itinerary).

Is there a particular type I should be looking for or am I out of luck?

For cheap. Not really possible.
U could potentially trade for lots of miles and try to upgrade with Miles.

I think this is the only option IF your fare class allows it.

Probably 60k+ miles per ticket to upgrade. OP can find out how many miles needed by calling/tweeting DL. May also see the option online, but not sure. As far as I know, the number of miles needed is not published, and may vary depending on the fare class purchased (cheapest coach fares will cost more miles to upgrade than more expensive coach fares).