Just checking since packs 1, 2, and 3 don't appear to be listed for sale anymore. I don't know if they were supported in G6 and 6.5. The last one I purchased was G3.
Be sure you are not confusing the older G3 Add-On Packs (they are not the same as the Expansion Packs). These are still available as free downloads, however, and are compatible with RF7 - but your original disks will not work.
Expansion Packs 1,2,3 will work with RF7 just like they do for 6.5. (I have all expansion packs) as far as the add-on's they are downloadable or if you have expansion pack 6 they do get installed with that expansion pack.
I really did mean all the Expansion Packs and Mega Packs will work with RealFlight 7.
EP1-3 are discontinued products. I can understand why this might cause confusion. While not direct replacements, the Mega Packs do more or less take their place by making most of that EP content available in another form. But if you already own EP1-3, they will work in RF7.
After installing the RF7 upgrade, I still have 6.5 with all my additional models from the RF Expansion Packs, Airplane and Helicopter Mega Packs LISTED only under 6.5.
I found that re-installation is not necessary ... you can copy the correct files into the new directory. There are other old threads that explain this and you should be familiar with using Windows file explorer. I did not try the upgrade utility mentioned above.