You might start with the three main "Alliances"...
Star Alliance
Oneworld
Skyteam
Qualifying travel* on any member of those alliances can be credited to the program of any other member airline.
For example.. My only FF program is NZ's "Airpoints".. but more than half of my annual credits to that program come from flying on SQ/TG/OZ/UA/US etc....
In addition to that there are some "One off" airline groupings/pairings that allow crediting... in some cases only "redeemable" miles rather than "Status" earning... I believe EK and UA have that relationship???
* Some deep discount fares may only credit to the program of the operating airline, or may credit at a reduced %, or may not credit at all....
Virgin Atlantic seem to have a large number of specific codeshare routings on which one can earn to their own program... but they don't seem to give any easily found info about crediting TO others... I did just have a quick look it must be said...